Food service products comprising polyester compositions formed from 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol

ABSTRACT

Described are food storage containers comprising polyester compositions comprising polyesters which comprise (a) a dicarboxylic acid component having terephthalic acid residues; optionally, aromatic dicarboxylic acid residues or aliphatic dicarboxylic acid residues or ester residues thereof; 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and 1,4-cyclohexanedimethanol residues.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 60/691,567 filed on Jun. 17, 2005, U.S. Provisional Application Ser. No. 60/731,454 filed on Oct. 28, 2005, U.S. Provisional Application Ser. No. 60/731,389, filed on Oct. 28, 2005, U.S. Provisional Application Ser. No. 60/739,058, filed on Nov. 22, 2005, and U.S. Provisional Application Ser. No. 60/738,869, filed on Nov. 22, 2005, U.S. Provisional Application Ser. No. 60/750,692 filed on Dec. 15, 2005, U.S. Provisional Application Ser. No. 60/750,693, filed on Dec. 15, 2005, U.S. Provisional Application Ser. No. 60/750,682, filed on Dec. 15, 2005, and U.S. Provisional Application Ser. No. 60/750,547, filed on Dec. 15, 2005, all of which are hereby incorporated by this reference in their entireties.

FIELD OF THE INVENTION

The present invention generally relates to food storage containers comprising a polyester compositions made from terephthalic acid, or an ester thereof, or mixtures thereof, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol, having a certain combination of two or more of high impact strengths, high glass transition temperature (T_(g)), toughness, certain inherent viscosities, low ductile-to-brittle transition temperatures, good color and clarity, low densities, chemical resistance, hydrolytic stability, and long crystallization half-times, which allow them to be easily formed into articles. For example, the food storage containers of the present invention can have a combination of two or more of the following properties: toughness, clarity, chemical resistance, Tg, and hydrolytic stability.

BACKGROUND OF THE INVENTION

Food storage containers can be produced with a variety of plastic materials by a variety of processes (extrusion blow molding, injection molding, etc.). For example, polyethylene terephthalate (PET) is a common material used to make containers, such as those used by the food service industry to store and/or serve food. Unfortunately, PET becomes difficult to use when the fill temperature of the container becomes elevated. Higher temperature materials, such as polycarbonate or acrylic polymers, can be made into containers, but the barrier of these materials is poor, limiting the types of products that these materials can contain.

Thus, there is a need in the industry for a high-heat material with good barrier that can be fabricated into containers.

Poly(1,4-cyclohexylenedimethylene) terephthalate (PCT), a polyester based solely on terephthalic acid or an ester thereof and 1,4-cyclohexanedimethanol, is known in the art and is commercially available. This polyester crystallizes rapidly upon cooling from the melt, making it very difficult to form amorphous articles by methods known in the art such as extrusion, injection molding, and the like. In order to slow down the crystallization rate of PCT, copolyesters can be prepared containing additional dicarboxylic acids or glycols such as isophthalic acid or ethylene glycol. These ethylene glycol- or isophthalic acid-modified PCTs are also known in the art and are commercially available.

One common copolyester used to produce films, sheeting, and molded articles is made from terephthalic acid, 1,4-cyclohexanedimethanol, and ethylene glycol. While these copolyesters are useful in many end-use applications, they exhibit deficiencies in properties such as glass transition temperature and impact strength when sufficient modifying ethylene glycol is included in the formulation to provide for long crystallization half-times. For example, copolyesters made from terephthalic acid, 1,4-cyclohexanedimethanol, and ethylene glycol with sufficiently long crystallization half-times can provide amorphous products that exhibit what is believed to be undesirably higher ductile-to-brittle transition temperatures and lower glass transition temperatures than the compositions revealed herein.

The polycarbonate of 4,4′-isopropylidenediphenol (bisphenol A polycarbonate) has been used as an alternative for polyesters known in the art and is a well known engineering molding plastic. Bisphenol A polycarbonate is a clear, high-performance plastic having good physical properties such as dimensional stability, high heat resistance, and good impact strength. Although bisphenol-A polycarbonate has many good physical properties, its relatively high melt viscosity leads to poor melt processability and the polycarbonate exhibits poor chemical resistance. It is also difficult to thermoform.

Polymers containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol have also been generally described in the art. Generally, however, these polymers exhibit high inherent viscosities, high melt viscosities and/or high Tgs (glass transition temperatures) such that the equipment used in industry can be insufficient to manufacture or post polymerization process these materials.

Thus, there is a need in the art for food storage containers comprising at least one polymer having a combination of two or more properties, chosen from at least one of the following: toughness, high glass transition temperatures, high impact strength, hydrolytic stability, chemical resistance, long crystallization half-times, low ductile to brittle transition temperatures, good color, and clarity, lower density and/or thermoformability of polyesters while retaining processability on the standard equipment used in the industry.

SUMMARY OF THE INVENTION

It is believed that certain food storage containers comprising polyester compositions formed from terephthalic acid, an ester thereof, or mixtures thereof, 1,4-cyclohexanedimethanol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol with certain monomer compositions, inherent viscosities and/or glass transition temperatures are superior to polyesters known in the art and to polycarbonate with respect to one or more of high impact strengths, hydrolytic stability, toughness, chemical resistance, good color and clarity, long crystallization half-times, low ductile to brittle transition temperatures, lower specific gravity, and thermoformability. These compositions are believed to be similar to polycarbonate in heat resistance and are still processable on the standard industry equipment.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(a) a dicarboxylic acid component comprising:

-   -   i) 70 to 100 mole % of terephthalic acid residues;     -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having         up to 20 carbon atoms; and     -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues         having up to 16 carbon atoms; and

(b) a glycol component comprising:

-   -   i) 20 to 99 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol         residues; and     -   ii) 1 to 80 mole % of 1,4-cyclohexanedimethanol residues,

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.35 to 1.2 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 110 to 200° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(a) a dicarboxylic acid component comprising:

-   -   i) 70 to 100 mole % of terephthalic acid residues;     -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having         up to 20 carbon atoms; and     -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues         having up to 16 carbon atoms; and

(b) a glycol component comprising:

-   -   i) 40 to 70 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol         residues; and     -   ii) 30 to 60 mole % of 1,4-cyclohexanedimethanol residues,

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.35 to 1.2 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 120 to 150° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(a) a dicarboxylic acid component comprising:

-   -   i) 70 to 100 mole % of terephthalic acid residues;     -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having         up to 20 carbon atoms; and     -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues         having up to 16 carbon atoms; and

(b) a glycol component comprising:

-   -   i) 40 to 65 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol         residues; and     -   ii) 35 to 60 mole % of 1,4-cyclohexanedimethanol residues,

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.35 to 0.75 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 120 to 150° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(a) a dicarboxylic acid component comprising:

-   -   i) 70 to 100 mole % of terephthalic acid residues;     -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having         up to 20 carbon atoms; and     -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues         having up to 16 carbon atoms; and

(b) a glycol component comprising:

-   -   i) 40 to 65 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol         residues; and     -   ii) 35 to 60 mole % of 1,4-cyclohexanedimethanol residues,

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.60 to 0.72 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 120 to 140° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(a) a dicarboxylic acid component comprising:

-   -   i) 70 to 100 mole % of terephthalic acid residues;     -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having         up to 20 carbon atoms; and     -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues         having up to 16 carbon atoms; and

(b) a glycol component comprising:

-   -   i) 45 to 60 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol         residues; and     -   ii) 40 to 55 mole % of 1,4-cyclohexanedimethanol residues,

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.35 to 0.75 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 120 to 150° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(a) a dicarboxylic acid component comprising:

-   -   i) 70 to 100 mole % of terephthalic acid residues;     -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having         up to 20 carbon atoms; and     -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues         having up to 16 carbon atoms; and

(b) a glycol component comprising:

-   -   i) 45 to 60 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol         residues; and     -   ii) 44 to 55 mole % of 1,4-cyclohexanedimethanol residues,

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.60 to 0.72 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 120 to 140° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(a) a dicarboxylic acid component comprising:

-   -   i) 70 to 100 mole % of terephthalic acid residues;     -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having         up to 20 carbon atoms; and     -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues         having up to 16 carbon atoms; and

(b) a glycol component comprising:

-   -   i) 40 to 90 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol         residues; and     -   ii) 10 to 60 mole % of 1,4-cyclohexanedimethanol residues,

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.35 to 1.2 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 120 to 190° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(I) at least one polyester which comprises:

-   -   (a) a dicarboxylic acid component comprising:         -   i) 70 to 100 mole % of terephthalic acid, an ester thereof,             or mixtures thereof;         -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues             having up to 20 carbon atoms; and         -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues             having up to 16 carbon atoms; and     -   (b) a glycol component comprising:         -   i) 20 to 99 mole % of             2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and         -   ii) 1 to 80 mole % of 1,4-cyclohexanedimethanol residues,             and

(II) residues of at least one branching agent;

wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is from 0.35 to 1.2 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; and

wherein the polyester has a Tg of from 110 to 200° C.

In one aspect, the invention relates to a food storage container comprising at least one polyester composition comprising at least one polyester, which comprises:

(I) at least one polyester which comprises:

-   -   (a) a dicarboxylic acid component comprising:         -   i) 70 to 100 mole % of terephthalic acid residues;         -   ii) 0 to 30 mole % of aromatic dicarboxylic acid residues             having up to 20 carbon atoms; and         -   iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues             having up to 16 carbon atoms; and     -   (b) a glycol component comprising:         -   i) 20 to 99 mole % of             2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and         -   ii) 1 to 80 mole % of 1,4-cyclohexanedimethanol residues,             and

(II) at least one thermal stabilizer or reaction products thereof;

wherein the total mole % of the dicarboxylic acid component is 100 mole %, and the total mole % of the glycol component is 100 mole %; and

wherein the inherent viscosity of the polyester is 0.35 to 1.2 dL/g as determined in 60/40 (wt/wt)phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.;

wherein the polyester has a Tg from 110 to 200° C.

In one aspect, the polyester composition contains at least one polycarbonate.

In one aspect, the polyester composition contains no polycarbonate.

In one aspect, the polyesters useful in the invention contain less than 15 mole % ethylene glycol residues, such as, for example, 0.01 to less than 15 mole % ethylene glycol residues.

In one aspect, the polyesters useful in the invention contain no ethylene glycol residues.

In one aspect the polyester compositions useful in the invention contain at least one thermal stabilizer and/or reaction products thereof.

In one aspect, the polyesters useful in the invention contain no branching agent, or alternatively, at least one branching agent is added either prior to or during polymerization of the polyester.

In one aspect, the polyesters useful in the invention contain at least one branching agent without regard to the method or sequence in which it is added.

In one aspect, the polyesters useful in the invention are made from no 1,3-propanediol, or, 1,4-butanediol, either singly or in combination. In other aspects, 1,3-propanediol or 1,4-butanediol, either singly or in combination, may be used in the making of the polyesters useful in this invention.

In one aspect of the invention, the mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol useful in certain polyesters useful in the invention is greater than 50 mole % or greater than 55 mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol or greater than 70 mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol; wherein the total mole percentage of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol and trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol is equal to a total of 100 mole %.

In one aspect of the invention, the mole % of the isomers of 2,2,4,4-tetramethyl-1,3-cyclobutanediol useful in certain polyesters useful in the invention is from 30 to 70 mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol or from 30 to 70 mole % of trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol, or from 40 to 60 mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol or from 40 to 60 mole % of trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol, wherein the total mole percentage of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol and trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol is equal to a total of 100 mole %.

In one aspect, the polyester compositions are useful in food storage containers including but not limited to extruded and/or molded articles including, but not limited to, extruded and/or molded articles including but not limited to, injection molded articles, extruded articles, cast extrusion articles, profile extrusion articles, extrusion molded articles, injection blow molded articles, injection stretch blow molded articles, extrusion blow molded articles, and extrusion stretch blow molded articles.

Also, in one aspect, use of the polyester compositions of the invention minimizes and/or eliminates the drying step prior to melt processing or thermoforming.

In one aspect, certain polyesters useful in the invention can be amorphous or semicrystalline. In one aspect, certain polyesters useful in the invention can have a relatively low crystallinity. Certain polyesters useful in the invention can thus have a substantially amorphous morphology, meaning that the polyesters comprise substantially unordered regions of polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the effect of comonomer on the fastest crystallization half-times of modified PCT copolyesters.

FIG. 2 is a graph showing the effect of comonomer on the brittle-to-ductile transition temperature (T_(bd)) in a notched Izod impact strength test (ASTM D256, ⅛-in thick, 10-mil notch).

FIG. 3 is a graph showing the effect of 2,2,4,4-tetramethyl-1,3-cyclobutanediol composition on the glass transition temperature (Tg) of the copolyester.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be understood more readily by reference to the following detailed description of certain embodiments of the invention and the working examples.

In accordance with the purpose(s) of this invention, certain embodiments of the invention are described in the Summary of the Invention and are further described herein below. Also, other embodiments of the invention are described herein.

It is believed that the polyester(s) and/or polyester composition(s) which are included in the food storage containers of the invention described herein can have a unique combination of two or more physical properties such as high impact strengths, moderate to high glass transition temperatures, chemical resistance, hydrolytic stability, toughness, low ductile-to-brittle transition temperatures, good color and clarity, low densities, long crystallization half-times, and good processability thereby easily permitting them to be formed into articles. In some of the embodiments of the invention, the polyesters have a unique combination of the properties of good impact strength, heat resistance, chemical resistance, density and/or the combination of the properties of good impact strength, heat resistance, and processability and/or the combination of two or more of the described properties, that have never before been believed to be present in food storage containers comprising the polyester compositions which comprise the polyester(s) as disclosed herein.

“Food storage container,” as used herein, are capable of storing and/or serving hot and/or cold food and/or beverages at temperatures customarily used for storing and serving foods and beverages, e.g., ranging from deep freezer temperatures to hot temperatures such as those in a low temperature oven or those used in hot beverage dispensers. In one embodiment, the food storage container can be sealed to reduce the rate of food oxidation. In another embodiment, the food storage container can be used to display and serve the food to dining customers.

In one embodiment, the containers are capable of being stored in a freezer, e.g., at temperatures less than 0° C., such as temperatures ranging from −20 to 0° C. (e.g., −18° C.). In another embodiment, the containers are capable of storing food in the refrigerator at temperatures ranging from greater than 0° C. (e.g., 2° C.) to 5° C. In another embodiment, the food storage containers can withstand steam treatments and/or commercial dishwasher conditions. In another embodiment, the containers are capable of withstanding microwave conditions.

Examples of food storage containers include buffet steam pans, buffet steam trays, food pans, hot and cold beverage dispensers (e.g. refrigerator beverage dispensers, automated hot or cold beverage dispensers), and food storage boxes.

In one embodiment, food storage containers have at least one additional property chosen from toughness, clarity, chemical resistance, Tg, and hydrolytic stability.

The term “polyester”, as used herein, is intended to include “copolyesters” and is understood to mean a synthetic polymer prepared by the reaction of one or more difunctional carboxylic acids and/or multifunctional carboxylic acids with one or more difunctional hydroxyl compounds and/or multifunctional hydroxyl compounds. Typically the difunctional carboxylic acid can be a dicarboxylic acid and the difunctional hydroxyl compound can be a dihydric alcohol such as, for example, glycols. Furthermore, as used in this application, the term “diacid” or “dicarboxylic acid” includes multifunctional acids, such as branching agents. The term “glycol” as used in this application includes, but is not limited to, diols, glycols, and/or multifunctional hydroxyl compounds. Alternatively, the difunctional carboxylic acid may be a hydroxy carboxylic acid such as, for example, p-hydroxybenzoic acid, and the difunctional hydroxyl compound may be an aromatic nucleus bearing 2 hydroxyl substituents such as, for example, hydroquinone. The term “residue”, as used herein, means any organic structure incorporated into a polymer through a polycondensation and/or an esterification reaction from the corresponding monomer. The term “repeating unit”, as used herein, means an organic structure having a dicarboxylic acid residue and a diol residue bonded through a carbonyloxy group. Thus, for example, the dicarboxylic acid residues may be derived from a dicarboxylic acid monomer or its associated acid halides, esters, salts, anhydrides, or mixtures thereof. As used herein, therefore, the term dicarboxylic acid is intended to include dicarboxylic acids and any derivative of a dicarboxylic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, or mixtures thereof, useful in a reaction process with a diol to make polyester. As used herein, the term “terephthalic acid” is intended to include terephthalic acid itself and residues thereof as well as any derivative of terephthalic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, or mixtures thereof or residues thereof useful in a reaction process with a diol to make polyester.

In one embodiment, terephthalic acid may be used as the starting material. In another embodiment, dimethyl terephthalate may be used as the starting material. In another embodiment, mixtures of terephthalic acid and dimethyl terephthalate may be used as the starting material and/or as an intermediate material.

The polyesters used in the present invention typically can be prepared from dicarboxylic acids and diols which react in substantially equal proportions and are incorporated into the polyester polymer as their corresponding residues. The polyesters of the present invention, therefore, can contain substantially equal molar proportions of acid residues (100 mole %) and diol (and/or multifunctional hydroxyl compounds) residues (100 mole %) such that the total moles of repeating units is equal to 100 mole %. The mole percentages provided in the present disclosure, therefore, may be based on the total moles of acid residues, the total moles of diol residues, or the total moles of repeating units. For example, a polyester containing 30 mole % isophthalic acid, based on the total acid residues, means the polyester contains 30 mole % isophthalic acid residues out of a total of 100 mole % acid residues. Thus, there are 30 moles of isophthalic acid residues among every 100 moles of acid residues. In another example, a polyester containing 30 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol, based on the total diol residues, means the polyester contains 30 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues out of a total of 100 mole % diol residues. Thus, there are 30 moles of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues among every 100 moles of diol residues.

In other aspects of the invention, the Tg of the polyesters useful in the food storage container(s) of the invention can be at least one of the following ranges: 110 to 200° C.; 110 to 190° C.; 110 to 180° C.; 110 to 170° C.; 110 to 160° C.; 110 to 155° C.; 110 to 150° C.; 110 to 145° C.; 110 to 140° C.; 110 to 138° C.; 110 to 135° C.; 110° C.; 110 to 125° C.; 110 to 120° C.; 110 to 115° C.; 115 to 200° C.; 115 to 190° C.; 115 to 180° C.; 115 to 170° C.; 115 to 160° C.; 115 to 155° C.; 115 to 150° C.; 115 to 145° C.; 115 to 140° C.; 115 to 138° C.; 115 to 135° C.; 110° C.; 115 to 125° C.; 115 to 120° C.; 120 to 200° C.; 120 to 190° C.; 120 to 180° C.; 120 to 170° C.; 120 to 160° C.; 120 to 155° C.; 120 to 150° C.; 120 to 145° C.; 110 to 130° C.; 120 to 138° C.; 120 to 135° C.; 120 to 130° C.; 125 to 200° C.; 125 to 190° C.; 125 to 180° C.; 125 to 170° C.; 125 to 160° C.; 125 to 155° C.; 125 to 150° C.; 125 to 145° C.; 125 to 140° C.; 125 to 138° C.; 125 to 135° C.; 127 to 200° C.; 127 to 190° C.; 127 to 180° C.; 127 to 170° C.; 127 to 160° C.; 127 to 150° C.; 127 to 145° C.; 127 to 140° C.; 127 to 138° C.; 127 to 135° C.; 130 to 200° C.; 130 to 190° C.; 130 to 180° C.; 130 to 170° C.; 130 to 160° C.; 130 to 155° C.; 130 to 150° C.; 130 to 145° C.; 130 to 140° C.; 130 to 138° C.; 130 to 135° C.; 135 to 200° C.; 135 to 190° C.; 135 to 180° C.; 135 to 170° C.; 135 to 160° C.; 135 to 155° C.; 135 to 150° C.; 135 to 145° C.; 135 to 140° C.; 140 to 200° C.; 140 to 190° C.; 140 to 180° C.; 140 to 170° C.; 140 to 160° C.; 140 to 155° C.; 140 to 150° C.; 140 to 145° C.; 148 to 200° C.; 148 to 190° C.; 148 to 180° C.; 148 to 170° C.; 148 to 160° C.; 148 to 155° C.; 148 to 150° C.; 150 to 200° C.; 150 to 190° C.; 150 to 180° C.; 150 to 170° C.; 150 to 160; 155 to 190° C.; 155 to 180° C.; 155 to 170° C.; and 155 to 165° C.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 20 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 80 mole % 1,4-cyclohexanedimethanol, 20 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 45 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 55 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 60 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 35 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 65 to 80 mole % 1,4-cyclohexanedimethanol; 20 to 30 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 70 to 80 mole % 1,4-cyclohexanedimethanol; and 20 to 25 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 75 to 80 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 25 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 75 mole % 1,4-cyclohexanedimethanol, 25 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 45 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 55 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 60 to 75 mole % 1,4-cyclohexanedimethanol; 25 to 35 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 65 to 75 mole % 1,4-cyclohexanedimethanol; and 25 to 30 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 70 to 75 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 30 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 70 mole % 1,4-cyclohexanedimethanol, 30 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to 70 mole % 1,4-cyclohexanedimethanol; 30 to less than 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and greater than 50 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 45 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 55 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 60 to 70 mole % 1,4-cyclohexanedimethanol; 30 to 35 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 65 to 70 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 35 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 65 mole % 1,4-cyclohexanedimethanol, 35 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to 65 mole % 1,4-cyclohexanedimethanol; 35 to less than 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and greater than 50 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 45 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 55 to 65 mole % 1,4-cyclohexanedimethanol; 35 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 60 to 65 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 37 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 63 mole % 1,4-cyclohexanedimethanol, 37 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 63 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 37 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to 63 mole % 1,4-cyclohexanedimethanol; 37 to less than 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and greater than 50 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 45 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 55 to 63 mole % 1,4-cyclohexanedimethanol; 37 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 60 to 63 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 40 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 60 mole % 1,4-cyclohexanedimethanol, 40 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 60 mole % 1,4-cyclohexanedimethanol; 40 to less than 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and greater than 50 to 60 mole % 1,4-cyclohexanedimethanol; 40 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to 60 mole % 1,4-cyclohexanedimethanol; and 40 to 45 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 55 to 60 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 45 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 55 mole % 1,4-cyclohexanedimethanol; 45 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 55 mole % 1,4-cyclohexanedimethanol; 45 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 55 mole % 1,4-cyclohexanedimethanol; 45 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 55 mole % 1,4-cyclohexanedimethanol; 45 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 55 mole % 1,4-cyclohexanedimethanol, 45 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 55 mole % 1,4-cyclohexanedimethanol; 45 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 55 mole % 1,4-cyclohexanedimethanol; 45 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 55 mole % 1,4-cyclohexanedimethanol; 45 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 55 mole % 1,4-cyclohexanedimethanol; greater than 45 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to less than 55 mole % 1,4-cyclohexanedimethanol; 45 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 55 mole % 1,4-cyclohexanedimethanol; and 45 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to 55 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: greater than 50 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to less than 50 mole % 1,4-cyclohexanedimethanol; greater than 50 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to less than 50 mole % 1,4-cyclohexanedimethanol; greater than 50 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to less than 50 mole % 1,4-cyclohexanedimethanol; greater than 50 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to less than 50 mole % 1,4-cyclohexanedimethanol; greater than 50 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to less than 50 mole % 1,4-cyclohexanedimethanol, greater than 50 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to less than 50 mole % 1,4-cyclohexanedimethanol; greater than 50 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to less than 50 mole % 1,4-cyclohexanedimethanol; greater than 50 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to less than 50 mole % 1,4-cyclohexanedimethanol; greater than 50 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to less than 50 mole % 1,4-cyclohexanedimethanol; and greater than 50 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to less than 50 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 50 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 50 mole % 1,4-cyclohexanedimethanol; 50 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 50 mole % 1,4-cyclohexanedimethanol; 50 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 50 mole % 1,4-cyclohexanedimethanol; 50 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 50 mole % 1,4-cyclohexanedimethanol; 50 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 50 mole % 1,4-cyclohexanedimethanol, 50 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 50 mole % 1,4-cyclohexanedimethanol; 50 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 50 mole % 1,4-cyclohexanedimethanol; 50 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 50 mole % 1,4-cyclohexanedimethanol; 50 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 50 mole % 1,4-cyclohexanedimethanol; and 50 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 50 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 55 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 45 mole % 1,4-cyclohexanedimethanol; 55 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 45 mole % 1,4-cyclohexanedimethanol; 55 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 45 mole % 1,4-cyclohexanedimethanol; 55 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 45 mole % 1,4-cyclohexanedimethanol; 55 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 45 mole % 1,4-cyclohexanedimethanol, 55 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 45 mole % 1,4-cyclohexanedimethanol; 55 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 45 mole % 1,4-cyclohexanedimethanol; 55 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 45 mole % 1,4-cyclohexanedimethanol; and 55 to 60 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 40 to 45 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 60 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 40 mole % 1,4-cyclohexanedimethanol; 60 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 40 mole % 1,4-cyclohexanedimethanol; 60 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 40 mole % 1,4-cyclohexanedimethanol; 60 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 40 mole % 1,4-cyclohexanedimethanol; 60 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 40 mole % 1,4-cyclohexanedimethanol, 60 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 40 mole % 1,4-cyclohexanedimethanol; and 60 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 30 to 40 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the invention include but are not limited to at least one of the following combinations of ranges: 65 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 35 mole % 1,4-cyclohexanedimethanol; 65 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 35 mole % 1,4-cyclohexanedimethanol; 65 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 35 mole % 1,4-cyclohexanedimethanol; 65 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 35 mole % 1,4-cyclohexanedimethanol; 65 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 35 mole % 1,4-cyclohexanedimethanol, 65 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 35 mole % 1,4-cyclohexanedimethanol; and 65 to 70 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 40 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 70 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 30 mole % 1,4-cyclohexanedimethanol; 70 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 30 mole % 1,4-cyclohexanedimethanol; 70 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 30 mole % 1,4-cyclohexanedimethanol; 70 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 30 mole % 1,4-cyclohexanedimethanol; 70 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 30 mole % 1,4-cyclohexanedimethanol, and 70 to 75 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 25 to 30 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 75 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 25 mole % 1,4-cyclohexanedimethanol; 75 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 25 mole % 1,4-cyclohexanedimethanol; 75 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 25 mole % 1,4-cyclohexanedimethanol; 75 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 25 mole % 1,4-cyclohexanedimethanol, and 75 to 80 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 20 to 25 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: 80 to 99 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 1 to 20 mole % 1,4-cyclohexanedimethanol; 80 to 95 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 5 to 20 mole % 1,4-cyclohexanedimethanol; 80 to 90 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 10 to 20 mole % 1,4-cyclohexanedimethanol, and 80 to 85 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 15 to 20 mole % 1,4-cyclohexanedimethanol.

In other aspects of the invention, the glycol component for the polyesters useful in the food storage container(s) of the invention include but are not limited to at least one of the following combinations of ranges: greater than 45 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to less than 55 mole % 1,4-cyclohexanedimethanol; greater than 45 to 50 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 50 to less than 55 mole % 1,4-cyclohexanedimethanol; 46 to 55 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 45 to 54 mole % 1,4-cyclohexanedimethanol; and 46 to 65 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and 35 to 54 mole % 1,4-cyclohexanedimethanol.

In addition to the diols set forth above, the polyesters useful in the polyester compositions of the food storage container(s) of the invention may also be made from 1,3-propanediol, 1,4-butanediol, or mixtures thereof. It is contemplated that compositions of the invention made from 1,3-propanediol, 1,4-butanediol, or mixtures thereof can possess at least one of the Tg ranges described herein, at least one of the inherent viscosity ranges described herein, and/or at least one of the glycol or diacid ranges described herein. In addition or in the alternative, the polyesters made from 1,3-propanediol or 1,4-butanediol or mixtures thereof may also be made from 1,4-cyclohexanedmethanol in at least one of the following amounts: from 0.1 to 99 mole %; from 0.1 to 90 mole %; from 0.1 to 80 mole %; from 0.1 to 70 mole %; from 0.1 to 60 mole %; from 0.1 to 50 mole %; from 0.1 to 40 mole %; from 0.1 to 35 mole %; from 0.1 to 30 mole %; from 0.1 to 25 mole %; from 0.1 to 20 mole %; from 0.1 to 15 mole %; from 0.1 to 10 mole %; from 0.1 to 5 mole %; from 1 to 99 mole %; from 1 to 90 mole %, from 1 to 80 mole %; from 1 to 70 mole %; from 1 to 60 mole %; from 1 to 50 mole %; from 1 to 40 mole %; from 1 to 35 mole %; from 1 to 30 mole %; from 1 to 25 mole %; from 1 to 20 mole %; from 1 to 15 mole %; from 1 to 10 mole %; from 1 to 5 mole %; from 5 to 99 mole %, from 5 to 90 mole %, from 5 to 80 mole %; 5 to 70 mole %; from 5 to 60 mole %; from 5 to 50 mole %; from 5 to 40 mole %; from 5 to 35 mole %; from 5 to 30 mole %; from 5 to 25 mole %; from 5 to 20 mole %; and from 5 to 15 mole %; from 5 to 10 mole %; from 10 to 99 mole %; from 10 to 90 mole %; from 10 to 80 mole %; from 10 to 70 mole %; from 10 to 60 mole %; from 10 to 50 mole %; from 10 to 40 mole %; from 10 to 35 mole %; from 10 to 30 mole %; from 10 to 25 mole %; from 10 to 20 mole %; from 10 to 15 mole %; from 20 to 99 mole %; from 20 to 90 mole %; from 20 to 80 mole %; from 20 to 70 mole %; from 20 to 60 mole %; from 20 to 50 mole %; from 20 to 40 mole %; from 20 to 35 mole %; from 20 to 30 mole %; and from 20 to 25 mole

For certain embodiments of the invention, the polyesters useful in the invention may exhibit at least one of the following inherent viscosities as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.: 0.35 to 1.2 dL/g; 0.35 to 1.1 dL/g; 0.35 to 1 dL/g; 0.35 to less than 1 dL/g; 0.35 to 0.98 dL/g; 0.35 to 0.95 dL/g; 0.35 to 0.90 dL/g; 0.35 to 0.85 dL/g; 0.35 to 0.80 dL/g; 0.35 to 0.75 dL/g; 0.35 to less than 0.75 dL/g; 0.35 to 0.72 dL/g; 0.35 to 0.70 dL/g; 0.35 to less than 0.70 dL/g; 0.35 to 0.68 dL/g; 0.35 to less than 0.68 dL/g; 0.35 to 0.65 dL/g; 0.40 to 1.2 dL/g; 0.40 to 1.1 dL/g; 0.40 to 1 dL/g; 0.40 to less than 1 dL/g; 0.40 to 0.98 dL/g; 0.40 to 0.95 dL/g; 0.40 to 0.90 dL/g; 0.40 to 0.85 dL/g; 0.40 to 0.80 dL/g; 0.40 to 0.75 dL/g; 0.40 to less than 0.75 dL/g; 0.40 to 0.72 dL/g; 0.40 to 0.70 dL/g; 0.40 to less than 0.70 dL/g; 0.40 to 0.68 dL/g; 0.40 to less than 0.68 dL/g; 0.40 to 0.65 dL/g; greater than 0.42 to 1.2 dL/g; greater than 0.42 to 1.1 dL/g; greater than 0.42 to 1 dL/g; greater than 0.42 to less than 1 dL/g; greater than 0.42 to 0.98 dL/g; greater than 0.42 to 0.95 dL/g; greater than 0.42 to 0.90 dL/g; greater than 0.42 to 0.85 dL/g; greater than 0.42 to 0.80 dL/g; greater than 0.42 to 0.75 dL/g; greater than 0.42 to less than 0.75 dL/g; greater than 0.42 to 0.72 dL/g; greater than 0.42 to less than 0.70 dL/g; greater than 0.42 to 0.68 dL/g; greater than 0.42 to less than 0.68 dL/g; and greater than 0.42 to 0.65 dL/g.

For certain embodiments of the invention, the polyesters useful in the invention may exhibit at least one of the following inherent viscosities as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.: 0.45 to 1.2 dL/g; 0.45 to 1.1 dL/g; 0.45 to 1 dL/g; 0.45 to 0.98 dL/g; 0.45 to 0.95 dL/g; 0.45 to 0.90 dL/g; 0.45 to 0.85 dL/g; 0.45 to 0.80 dL/g; 0.45 to 0.75 dL/g; 0.45 to less than 0.75 dL/g; 0.45 to 0.72 dL/g; 0.45 to 0.70 dL/g; 0.45 to less than 0.70 dL/g; 0.45 to 0.68 dL/g; 0.45 to less than 0.68 dL/g; 0.45 to 0.65 dL/g; 0.50 to 1.2 dL/g; 0.50 to 1.1 dL/g; 0.50 to 1 dL/g; 0.50 to less than 1 dL/g; 0.50 to 0.98 dL/g; 0.50 to 0.95 dL/g; 0.50 to 0.90 dL/g; 0.50 to 0.85 dL/g; 0.50 to 0.80 dL/g; 0.50 to 0.75 dL/g; 0.50 to less than 0.75 dL/g; 0.50 to 0.72 dL/g; 0.50 to 0.70 dL/g; 0.50 to less than 0.70 dL/g; 0.50 to 0.68 dL/g; 0.50 to less than 0.68 dL/g; 0.50 to 0.65 dL/g; 0.55 to 1.2 dL/g; 0.55 to 1.1 dL/g; 0.55 to 1 dL/g; 0.55 to less than 1 dL/g; 0.55 to 0.98 dL/g; 0.55 to 0.95 dL/g; 0.55 to 0.90 dL/g; 0.55 to 0.85 dL/g; 0.55 to 0.80 dL/g; 0.55 to 0.75 dL/g; 0.55 to less than 0.75 dL/g; 0.55 to 0.72 dL/g; 0.55 to 0.70 dL/g; 0.55 to less than 0.70 dL/g; 0.55 to 0.68 dL/g; 0.55 to less than 0.68 dL/g; 0.55 to 0.65 dL/g; 0.58 to 1.2 dL/g; 0.58 to 1.1 dL/g; 0.58 to 1 dL/g; 0.58 to less than 1 dL/g; 0.58 to 0.98 dL/g; 0.58 to 0.95 dL/g; 0.58 to 0.90 dL/g; 0.58 to 0.85 dL/g; 0.58 to 0.80 dL/g; 0.58 to 0.75 dL/g; 0.58 to less than 0.75 dL/g; 0.58 to 0.72 dL/g; 0.58 to 0.70 dL/g; 0.58 to less than 0.70 dL/g; 0.58 to 0.68 dL/g; 0.58 to less than 0.68 dL/g; 0.58 to 0.65 dL/g; 0.60 to 1.2 dL/g; 0.60 to 1.1 dL/g; 0.60 to 1 dL/g; 0.60 to less than 1 dL/g; 0.60 to 0.98 dL/g; 0.60 to 0.95 dL/g; 0.60 to 0.90 dL/g; 0.60 to 0.85 dL/g; 0.60 to 0.80 dL/g; 0.60 to 0.75 dL/g; 0.60 to less than 0.75 dL/g; 0.60 to 0.72 dL/g; 0.60 to 0.70 dL/g; 0.60 to less than 0.70 dL/g; 0.60 to 0.68 dL/g; 0.60 to less than 0.68 dL/g; 0.60 to 0.65 dL/g; 0.65 to 1.2 dL/g; 0.65 to 1.1 dL/g; 0.65 to 1 dL/g; 0.65 to less than 1 dL/g; 0.65 to 0.98 dL/g; 0.65 to 0.95 dL/g; 0.65 to 0.90 dL/g; 0.65 to 0.85 dL/g; 0.65 to 0.80 dL/g; 0.65 to 0.75 dL/g; 0.65 to less than 0.75 dL/g; 0.65 to 0.72 dL/g; 0.65 to 0.70 dL/g; 0.65 to less than 0.70 dL/g; 0.68 to 1.2 dL/g; 0.68 to 1.1 dL/g; 0.68 to 1 dL/g; 0.68 to less than 1 dL/g; 0.68 to 0.98 dL/g; 0.68 to 0.95 dL/g; 0.68 to 0.90 dL/g; 0.68 to 0.85 dL/g; 0.68 to 0.80 dL/g; 0.68 to 0.75 dL/g; 0.68 to less than 0.75 dL/g; 0.68 to 0.72 dL/g; greater than 0.76 dL/g to 1.2 dL/g; greater than 0.76 dL/g to 1.1 dL/g; greater than 0.76 dL/g to 1 dL/g; greater than 0.76 dL/g to less than 1 dL/g; greater than 0.76 dL/g to 0.98 dL/g; greater than 0.76 dL/g to 0.95 dL/g; greater than 0.76 dL/g to 0.90 dL/g; greater than 0.80 dL/g to 1.2 dL/g; greater than 0.80 dL/g to 1.1 dL/g; greater than 0.80 dL/g to 1 dL/g; greater than 0.80 dL/g to less than 1 dL/g; greater than 0.80 dL/g to 1.2 dL/g; greater than 0.80 dL/g to 0.98 dL/g; greater than 0.80 dL/g to 0.95 dL/g; greater than 0.80 dL/g to 0.90 dL/g.

It is contemplated that compositions useful in the food storage container(s) of the invention can possess at least one of the inherent viscosity ranges described herein and at least one of the monomer ranges for the compositions described herein unless otherwise stated. It is also contemplated that compositions useful in the food storage container(s) of the invention can posses at least one of the Tg ranges described herein and at least one of the monomer ranges for the compositions described herein unless otherwise stated. It is also contemplated that compositions useful in the food storage container(s) of the invention can posses at least one of the Tg ranges described herein, at least one of the inherent viscosity ranges described herein, and at least one of the monomer ranges for the compositions described herein unless otherwise stated.

For the desired polyester, the molar ratio of cis/trans 2,2,4,4-tetramethyl-1,3-cyclobutanediol can vary from the pure form of each or mixtures thereof. In certain embodiments, the molar percentages for cis and/or trans 2,2,4,4,-tetramethyl-1,3-cyclobutanediol are greater than 50 mole % cis and less than 50 mole % trans; or greater than 55 mole % cis and less than 45 mole % trans; or 30 to 70 mole % cis and 70 to 30% trans; or 40 to 60 mole % cis and 60 to 40 mole % trans; or 50 to 70 mole % trans and 50 to 30% cis or 50 to 70 mole % cis and 50 to 30% trans; or 60 to 70 mole % cis and 30 to 40 mole % trans; or greater than 70 mole cis and less than 30 mole % trans; wherein the total sum of the mole percentages for cis- and trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol is equal to 100 mole %. The molar ratio of cis/trans 1,4-cyclohexandimethanol can vary within the range of 50/50 to 0/100, such as between 40/60 to 20/80.

In certain embodiments, terephthalic acid or an ester thereof, such as, for example, dimethyl terephthalate, or a mixture of terephthalic acid and an ester thereof, makes up most or all of the dicarboxylic acid component used to form the polyesters useful in the invention. In certain embodiments, terephthalic acid residues can make up a portion or all of the dicarboxylic acid component used to form the present polyester at a concentration of at least 70 mole %, such as at least 80 mole %, at least 90 mole %, at least 95 mole %, at least 99 mole %, or 100 mole %. In certain embodiments, higher amounts of terephthalic acid can be used in order to produce a higher impact strength polyester. In one embodiment, dimethyl terephthalate is part or all of the dicarboxylic acid component used to make the polyesters useful in the present invention. For the purposes of this disclosure, the terms “terephthalic acid” and “dimethyl terephthalate” are used interchangeably herein. In all embodiments, ranges of from 70 to 100 mole %; or 80 to 100 mole %; or 90 to 100 mole %; or 99 to 100 mole %; or 100 mole % terephthalic acid and/or dimethyl terephthalate and/or mixtures thereof may be used.

In addition to terephthalic acid, the dicarboxylic acid component of the polyester useful in the invention can comprise up to 30 mole %, up to 20 mole %, up to 10 mole %, up to 5 mole %, or up to 1 mole % of one or more modifying aromatic dicarboxylic acids. Yet another embodiment contains 0 mole % modifying aromatic dicarboxylic acids. Thus, if present, it is contemplated that the amount of one or more modifying aromatic dicarboxylic acids can range from any of these preceding endpoint values including, for example, from 0.01 to 30 mole %, 0.01 to 20 mole %, from 0.01 to 10 mole %, from 0.01 to 5 mole % and from 0.01 to 1 mole. In one embodiment, modifying aromatic dicarboxylic acids that may be used in the present invention include but are not limited to those having up to 20 carbon atoms, and which can be linear, para-oriented, or symmetrical. Examples of modifying aromatic dicarboxylic acids which may be used in this invention include, but are not limited to, isophthalic acid, 4,4′-biphenyldicarboxylic acid, 1,4-, 1,5-, 2,6-, 2,7-naphthalenedicarboxylic acid, and trans-4,4′-stilbenedicarboxylic acid, and esters thereof. In one embodiment, the modifying aromatic dicarboxylic acid is isophthalic acid.

The carboxylic acid component of the polyesters useful in the invention can be further modified with up to 10 mole %, such as up to 5 mole % or up to 1 mole % of one or more aliphatic dicarboxylic acids containing 2-16 carbon atoms, such as, for example, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic and dodecanedioic dicarboxylic acids. Certain embodiments can also comprise 0.01 or more mole %, such as 0.1 or more mole %, 1 or more mole %, 5 or more mole %, or 10 or more mole % of one or more modifying aliphatic dicarboxylic acids. Yet another embodiment contains 0 mole % modifying aliphatic dicarboxylic acids. Thus, if present, it is contemplated that the amount of one or more modifying aliphatic dicarboxylic acids can range from any of these preceding endpoint values including, for example, from 0.01 to 10 mole % and from 0.1 to 0.10 mole %. The total mole % of the dicarboxylic acid component is 100 mole %.

Esters of terephthalic acid and the other modifying dicarboxylic acids or their corresponding esters and/or salts may be used instead of the dicarboxylic acids. Suitable examples of dicarboxylic acid esters include, but are not limited to, the dimethyl, diethyl, dipropyl, diisopropyl, dibutyl, and diphenyl esters. In one embodiment, the esters are chosen from at least one of the following: methyl, ethyl, propyl, isopropyl, and phenyl esters.

The 1,4-cyclohexanedimethanol may be cis, trans, or a mixture thereof, for example a cis/trans ratio of 60:40 to 40:60. In another embodiment, the trans-1,4-cyclohexanedimethanol can be present in an amount of 60 to 80 mole %.

The glycol component of the polyester portion of the polyester composition useful in the invention can contain 25 mole % or less of one or more modifying glycols which are not 2,2,4,4-tetramethyl-1,3-cyclobutanediol or 1,4-cyclohexanedimethanol; in one embodiment, the polyesters useful in the invention may contain less than 15 mole % of one or more modifying glycols. In another embodiment, the polyesters useful in the invention can contain 10 mole % or less of one or more modifying glycols. In another embodiment, the polyesters useful in the invention can contain 5 mole % or less of one or more modifying glycols. In another embodiment, the polyesters useful in the invention can contain 3 mole % or less of one or more modifying glycols. In another embodiment, the polyesters useful in the invention can contain 0 mole % modifying glycols. Certain embodiments can also contain 0.01 or more mole %, such as 0.1 or more mole %, 1 or more mole %, 5 or more mole %, or 10 or more mole % of one or more modifying glycols. Thus, if present, it is contemplated that the amount of one or more modifying glycols can range from any of these preceding endpoint values including, for example, from 0.01 to 15 mole % and from 0.1 to 10 mole %.

Modifying glycols useful in the polyesters useful in the invention refer to diols other than 2,2,4,4,-tetramethyl-1,3-cyclobutanediol and 1,4-cyclohexanedimethanol and may contain 2 to 16 carbon atoms. Examples of suitable modifying glycols include, but are not limited to, ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, p-xylene glycol or mixtures thereof. In one embodiment, the modifying glycol is ethylene glycol. In another embodiment, the modifying glycols are 1,3-propanediol and/or 1,4-butanediol. In another embodiment, ethylene glycol is excluded as a modifying diol. In another embodiment, 1,3-propanediol and 1,4-butanediol are excluded as modifying diols. In another embodiment, 2,2-dimethyl-1,3-propanediol is excluded as a modifying diol.

The polyesters and/or the polycarbonates useful in the polyesters compositions of the invention can comprise from 0 to 10 mole percent, for example, from 0.01 to 5 mole percent, from 0.01 to 1 mole percent, from 0.05 to 5 mole percent, from 0.05 to 1 mole percent, or from 0.1 to 0.7 mole percent, based the total mole percentages of either the diol or diacid residues; respectively, of one or more residues of a branching monomer, also referred to herein as a branching agent, having 3 or more carboxyl substituents, hydroxyl substituents, or a combination thereof. In certain embodiments, the branching monomer or agent may be added prior to and/or during and/or after the polymerization of the polyester. The polyester(s) useful in the invention can thus be linear or branched. The polycarbonate can also be linear or branched. In certain embodiments, the branching monomer or agent may be added prior to and/or during and/or after the polymerization of the polycarbonate.

Examples of branching monomers include, but are not limited to, multifunctional acids or multifunctional alcohols such as trimellitic acid, trimellitic anhydride, pyromellitic dianhydride, trimethylolpropane, glycerol, pentaerythritol, citric acid, tartaric acid, 3-hydroxyglutaric acid and the like. In one embodiment, the branching monomer residues can comprise 0.1 to 0.7 mole percent of one or more residues chosen from at least one of the following: trimellitic anhydride, pyromellitic dianhydride, glycerol, sorbitol, 1,2,6-hexanetriol, pentaerythritol, trimethylolethane, and/or trimesic acid. The branching monomer may be added to the polyester reaction mixture or blended with the polyester in the form of a concentrate as described, for example, in U.S. Pat. Nos. 5,654,347 and 5,696,176, whose disclosure regarding branching monomers is incorporated herein by reference.

The glass transition temperature (Tg) of the polyesters useful in the invention was determined using a TA DSC 2920 from Thermal Analyst Instrument at a scan rate of 20° C./min.

Because of the long crystallization half-times (e.g., greater than 5 minutes) at 170° C. exhibited by certain polyesters useful in the present invention, it is possible to produce injection molded food storage container(s), injection blow molded food storage container(s), injection stretch blow molded food storage container(s), extrusion blow molded food storage container(s), extrusion stretch blow molded food storage container(s) and compression molded food storage container(s). The polyesters of the invention can be amorphous or semicrystalline. In one aspect, certain polyesters useful in the invention can have relatively low crystallinity. Certain polyesters useful in the invention can thus have a substantially amorphous morphology, meaning that the polyesters comprise substantially unordered regions of polymer.

In one embodiment, an “amorphous” polyester can have a crystallization half-time of greater than 5 minutes at 170° C. or greater than 10 minutes at 170° C. or greater than 50 minutes at 170° C. or greater than 100 minutes at 170° C. In one embodiment, of the invention, the crystallization half-times are greater than 1,000 minutes at 170° C. In another embodiment of the invention, the crystallization half-times of the polyesters useful in the invention are greater than 10,000 minutes at 170° C. The crystallization half time of the polyester, as used herein, may be measured using methods well-known to persons of skill in the art. For example, the crystallization half time of the polyester, t_(1/2), can be determined by measuring the light transmission of a sample via a laser and photo detector as a function of time on a temperature controlled hot stage. This measurement can be done by exposing the polymers to a temperature, T_(max), and then cooling it to the desired temperature. The sample can then be held at the desired temperature by a hot stage while transmission measurements are made as a function of time. Initially, the sample can be visually clear with high light transmission and becomes opaque as the sample crystallizes. The crystallization half-time is the time at which the light transmission is halfway between the initial transmission and the final transmission. T_(max) is defined as the temperature required to melt the crystalline domains of the sample (if crystalline domains are present). The sample can be heated to T_(max) to condition the sample prior to crystallization half time measurement. The absolute T_(max) temperature is different for each composition. For example PCT can be heated to some temperature greater than 290° C. to melt the crystalline domains.

As shown in Table 1 and FIG. 1 of the Examples, 2,2,4,4-tetramethyl-1,3-cyclobutanediol is more effective than other comonomers such ethylene glycol and isophthalic acid at increasing the crystallization half-time, i.e., the time required for a polymer to reach half of its maximum crystallinity. By decreasing the crystallization rate of PCT, i.e. increasing the crystallization half-time, amorphous articles based on modified PCT may be fabricated by methods known in the art such as extrusion, injection molding, and the like. As shown in Table 1, these materials can exhibit higher glass transition temperatures and lower densities than other modified PCT copolyesters.

The polyesters can exhibit an improvement in toughness combined with processability for some of the embodiments of the invention. For example, it is unexpected that lowering the inherent viscosity slightly of the polyesters useful in the invention results in a more processable melt viscosity while retaining good physical properties of the polyesters such as toughness and heat resistance.

Increasing the content of 1,4-cyclohexanedimethanol in a copolyester based on terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol can improve toughness, which can be determined by the brittle-to-ductile transition temperature in a notched Izod impact strength test as measured by ASTM D256. This toughness improvement, by lowering of the brittle-to-ductile transition temperature with 1,4-cyclohexanedimethanol, is believed to occur due to the flexibility and conformational behavior of 1,4-cyclohexanedimethanol in the copolyester. Incorporating 2,2,4,4-tetramethyl-1,3-cyclobutanediol into PCT is believed to improve toughness, by lowering the brittle-to-ductile transition temperature, as shown in Table 2 and FIG. 2 of the Examples. This is unexpected given the rigidity of 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

In one embodiment, the melt viscosity of the polyester(s) useful in the invention is less than 30,000 poise as measured a 1 radian/second on a rotary melt rheometer at 290° C. In another embodiment, the melt viscosity of the polyester(s) useful in the invention is less than 20,000 poise as measured a 1 radian/second on a rotary melt rheometer at 290° C.

In one embodiment, the melt viscosity of the polyester(s) useful in the invention is less than 15,000 poise as measured at 1 radian/second (rad/sec) on a rotary melt rheometer at 290° C. In one embodiment, the melt viscosity of the polyester(s) useful in the invention is less than 10,000 poise as measured at 1 radian/second (rad/sec) on a rotary melt rheometer at 290° C. In another embodiment, the melt viscosity of the polyester(s) useful in the invention is less than 6,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C. Viscosity at rad/sec is related to processability. Typical polymers have viscosities of less than 10,000 poise as measured at 1 radian/second when measured at their processing temperature. Polyesters are typically not processed above 290° C. Polycarbonate is typically processed at 290° C. The viscosity at 1 rad/sec of a typical 12 melt flow rate polycarbonate is 7000 poise at 290° C.

In one embodiment, certain polyesters useful in this invention are visually clear. The term “visually clear” is defined herein as an appreciable absence of cloudiness, haziness, and/or muddiness, when inspected visually. When the polyesters are blended with polycarbonate, including bisphenol A polycarbonates, the blends can be visually clear in one aspect of the invention.

The present polyesters possess one or more of the following properties. In other embodiments, the polyesters useful in the invention may have a yellowness index (ASTM D-1925) of less than 50, such as less than 20.

In one embodiment, polyesters of this invention exhibit superior notched toughness in thick sections. Notched Izod impact strength, as described in ASTM D256, is a common method of measuring toughness. When tested by the Izod method, polymers can exhibit either a complete break failure mode, where the test specimen breaks into two distinct parts, or a partial or no break failure mode, where the test specimen remains as one part. The complete break failure mode is associated with low energy failure. The partial and no break failure modes are associated with high energy failure. A typical thickness used to measure Izod toughness is ⅛″. At this thickness, very few polymers are believed to exhibit a partial or no break failure mode, polycarbonate being one notable example. When the thickness of the test specimen is increased to ¼″, however, no commercial amorphous materials exhibit a partial or no break failure mode. In one embodiment, compositions of the present example exhibit a no break failure mode when tested in Izod using a ¼″ thick specimen.

The polyesters useful in the invention can possess one or more of the following properties. In one embodiment, the polyesters useful in the invention exhibit a notched Izod impact strength of at least 150 J/m (3 ft-lb/in) at 23° C. with a 10-mil notch in a 3.2 mm (⅛-inch) thick bar determined according to ASTM D256; in one embodiment, the polyesters useful in the invention exhibit a notched Izod impact strength of at least (400 J/m) 7.5 ft-lb/in at 23° C. with a 10-mil notch in a 3.2 mm (⅛-inch) thick bar determined according to ASTM D256; in one embodiment, the polyesters useful in the invention exhibit a notched Izod impact strength of at least 1000 J/m (18 ft-lb/in) at 23° C. with a 10-mil notch in a 3.2 mm (⅛-inch) thick bar determined according to ASTM D256. In one embodiment, the polyesters useful in the invention exhibit a notched Izod impact strength of at least 150 J/m (3 ft-lb/in) at 23° C. with a 10-mil notch in a 6.4 mm (¼-inch) thick bar determined according to ASTM D256; in one embodiment, the polyesters useful in the invention exhibit a notched Izod impact strength of at least (400 J/m) 7.5 ft-lb/in at 23° C. with a 10-mil notch in a 6.4 mm (¼-inch) thick bar determined according to ASTM D256; in one embodiment, the polyesters useful in the food service products of the invention exhibit a notched Izod impact strength of at least 10 ft-lb/in at 23° C. with a 10-mil notch in a 3.2 mm (¼-inch) thick bar determined according to ASTM D256; in one embodiment, the polyesters useful in the invention exhibit a notched Izod impact strength of at least 1000 J/m (18 ft-lb/in) at 23° C. with a 10-mil notch in a 6.4 mm (¼-inch) thick bar determined according to ASTM D256.

In another embodiment, certain polyesters useful in the invention can exhibit an increase in notched Izod impact strength when measured at 0° C. of at least 3% or at least 5% or at least 10% or at least 15% as compared to the notched Izod impact strength when measured at −5° C. with a 10-mil notch in a ⅛-inch thick bar determined according to ASTM D256. In addition, certain other polyesters useful in the invention can also exhibit a retention of notched Izod impact strength within plus or minus 5% when measured at 0° C. through 30° C. with a 10-mil notch in a ⅛-inch thick bar determined according to ASTM D256.

In yet another embodiment, certain polyesters useful in the invention can exhibit a retention in notched Izod impact strength with a loss of no more than 70% when measured at 23° C. with a 10-mil notch in a ¼-inch thick bar determined according to ASTM D256 as compared to notched Izod impact strength for the same polyester when measured at the same temperature with a 10-mil notch in a ⅛-inch thick bar determined according to ASTM D256.

In one embodiment, the polyesters useful in the invention and/or the polyester compositions of the invention, with or without toners, can have color values L*, a* and b*, which can be determined using a Hunter Lab Ultrascan Spectra Colorimeter manufactured by Hunter Associates Lab Inc., Reston, Va. The color determinations are averages of values measured on either pellets of the polyesters or plaques or other items injection molded or extruded from them They are determined by the L*a*b* color system of the CIE (International Commission on Illumination) (translated), wherein L* represents the lightness coordinate, a* represents the red/green coordinate, and b* represents the yellow/blue coordinate. In certain embodiments, the b* values for the polyesters useful in the invention can be from −10 to less than 10 and the L* values can be from 50 to 90. In other embodiments, the b* values for the polyesters useful in the invention can be present in one of the following ranges: −10 to 9; −10 to 8; −10 to 7; −10 to 6; −10 to 5; −10 to 4; −10 to 3; −10 to 2; from −5 to 9; −5 to 8; −5 to 7; −5 to 6; −5 to 5; −5 to 4; −5 to 3; −5 to 2; 0 to 9; 0 to 8; 0 to 7; 0 to 6; 0 to 5; 0 to 4; 0 to 3; 0 to 2; 1 to 10; 1 to 9; 1 to 8; 1 to 7; 1 to 6; 1 to 5; 1 to 4; 1 to 3; and 1 to 2. In other embodiments, the L* value for the polyesters useful in the invention can be present in one of the following ranges: 50 to 60; 50 to 70; 50 to 80; 50 to 90; 60 to 70; 60 to 80; 60 to 90; 70 to 80; 79 to 90.

In one embodiment, the polyesters useful in the invention exhibit a ductile-to-brittle transition temperature of less than 0° C. based on a 10-mil notch in a ⅛-inch thick bar as defined by ASTM D256.

In one embodiment, the polyesters useful in the invention can exhibit at least one of the following densities: a density of less than 1.3 g/ml at 23° C.; a density of less than 1.2 g/ml at 23° C.; a density of less than 1.18 g/ml at 23° C.; a density of 0.80 to 1.3 g/ml at 23° C.; a density of 0.80 to 1.2 g/ml at 23° C.; a density of 0.80 to less than 1.2 g/ml at 23° C.; a density of 1.0 to 1.3 g/ml at 23° C.; a density of 1.0 to 1.2 g/ml at 23° C.; a density of 1.0 to 1.1 g/ml at 23° C.; a density of 1.13 to 1.3 g/ml at 23° C.; a density of 1.13 to 1.2 g/ml at 23° C.

In some embodiments, use of the polyester compositions useful in the invention minimizes and/or eliminates the drying step prior to melt processing and/or thermoforming.

The polyester portion of the polyester compositions useful in the invention can be made by processes known from the literature such as, for example, by processes in homogenous solution, by transesterification processes in the melt, and by two phase interfacial processes. Suitable methods include, but are not limited to, the steps of reacting one or more dicarboxylic acids with one or more glycols at a temperature of 100° C. to 315° C. at a pressure of 0.1 to 760 mm Hg for a time sufficient to form a polyester. See U.S. Pat. No. 3,772,405 for methods of producing polyesters, the disclosure regarding such methods is hereby incorporated herein by reference.

In another aspect, the invention relates to food storage container(s) comprising a polyester produced by a process comprising:

(I) heating a mixture comprising the monomers useful in any of the polyesters in the invention in the presence of a catalyst at a temperature of 150 to 240° C. for a time sufficient to produce an initial polyester;

(II) heating the initial polyester of step (I) at a temperature of 240 to 320° C. for 1 to 4 hours; and

(III) removing any unreacted glycols.

Suitable catalysts for use in this process include, but are not limited to, organo-zinc or tin compounds. The use of this type of catalyst is well known in the art. Examples of catalysts useful in the present invention include, but are not limited to, zinc acetate, butyltin tris-2-ethylhexanoate, dibutyltin diacetate, and dibutyltin oxide. Other catalysts may include, but are not limited to, those based on titanium, zinc, manganese, lithium, germanium, and cobalt. Catalyst amounts can range from 10 ppm to 20,000 ppm or 10 to 10,000 ppm, or 10 to 5000 ppm or 10 to 1000 ppm or 10 to 500 ppm, or 10 to 300 ppm or 10 to 250 based on the catalyst metal and based on the weight of the final polymer. The process can be carried out in either a batch or continuous process.

Typically, step (I) can be carried out until 50% by weight or more of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol has been reacted. Step (I) may be carried out under pressure, ranging from atmospheric pressure to 100 psig. The term “reaction product” as used in connection with any of the catalysts useful in the invention refers to any product of a polycondensation or esterification reaction with the catalyst and any of the monomers used in making the polyester as well as the product of a polycondensation or esterification reaction between the catalyst and any other type of additive.

Typically, Step (II) and Step (III) can be conducted at the same time. These steps can be carried out by methods known in the art such as by placing the reaction mixture under a pressure ranging from 0.002 psig to below atmospheric pressure, or by blowing hot nitrogen gas over the mixture.

The invention further relates to a polyester product made by the process described above.

The invention further relates to a polymer blend. The blend comprises:

(a) 5 to 95 wt % of at least one of the polyesters described above; and

(b) 5 to 95 wt % of at least one polymeric component.

Suitable examples of polymeric components include, but are not limited to, nylon, polyesters different from those described herein, polyamides such as ZYTEL® from DuPont; polystyrene, polystyrene copolymers, styrene acrylonitrile copolymers, acrylonitrile butadiene styrene copolymers, poly(methylmethacrylate), acrylic copolymers, poly(ether-imides) such as ULTEM® (a poly(ether-imide) from General Electric); polyphenylene oxides such as poly(2,6-dimethylphenylene oxide) or poly(phenylene oxide)/polystyrene blends such as NORYL 1000® (a blend of poly(2,6-dimethylphenylene oxide) and polystyrene resins from General Electric); polyphenylene sulfides; polyphenylene sulfide/sulfones; poly(ester-carbonates); polycarbonates such as LEXAN® (a polycarbonate from General Electric); polysulfones; polysulfone ethers; and poly(ether-ketones) of aromatic dihydroxy compounds; or mixtures of any of the other foregoing polymers. The blends can be prepared by conventional processing techniques known in the art, such as melt blending or solution blending. In one embodiment, the polycarbonate is not present in the polyester composition. If polycarbonate is used in a blend in the polyester compositions useful in the invention, the blends can be visually clear. However, the polyester compositions useful in the invention also contemplate the exclusion of polycarbonate as well as the inclusion of polycarbonate.

Polycarbonates useful in the invention may be prepared according to known procedures, for example, by reacting the dihydroxyaromatic compound with a carbonate precursor such as phosgene, a haloformate or a carbonate ester, a molecular weight regulator, an acid acceptor and a catalyst. Methods for preparing polycarbonates are known in the art and are described, for example, in U.S. Pat. No. 4,452,933, where the disclosure regarding the preparation of polycarbonates is hereby incorporated by reference herein.

Examples of suitable carbonate precursors include, but are not limited to, carbonyl bromide, carbonyl chloride, or mixtures thereof; diphenyl carbonate; a di(halophenyl)carbonate, e.g., di(trichlorophenyl)carbonate, di(tribromophenyl)carbonate, and the like; di(alkylphenyl)carbonate, e.g., di(tolyl)carbonate; di(naphthyl)carbonate; di(chloronaphthyl)carbonate, or mixtures thereof; and bis-haloformates of dihydric phenols.

Examples of suitable molecular weight regulators include, but are not limited to, phenol, cyclohexanol, methanol, alkylated phenols, such as octylphenol, para-tertiary-butyl-phenol, and the like. In one embodiment, the molecular weight regulator is phenol or an alkylated phenol.

The acid acceptor may be either an organic or an inorganic acid acceptor. A suitable organic acid acceptor can be a tertiary amine and includes, but is not limited to, such materials as pyridine, triethylamine, dimethylaniline, tributylamine, and the like. The inorganic acid acceptor can be either a hydroxide, a carbonate, a bicarbonate, or a phosphate of an alkali or alkaline earth metal.

The catalysts that can be used include, but are not limited to, those that typically aid the polymerization of the monomer with phosgene. Suitable catalysts include, but are not limited to, tertiary amines such as triethylamine, tripropylamine, N,N-dimethylaniline, quaternary ammonium compounds such as, for example, tetraethylammonium bromide, cetyl triethyl ammonium bromide, tetra-n-heptylammonium iodide, tetra-n-propyl ammonium bromide, tetramethyl ammonium chloride, tetra-methyl ammonium hydroxide, tetra-n-butyl ammonium iodide, benzyltrimethyl ammonium chloride and quaternary phosphonium compounds such as, for example, n-butyltriphenyl phosphonium bromide and methyltriphenyl phosphonium bromide.

The polycarbonates useful in the polyester compositions of the invention also may be copolyestercarbonates such as those described in U.S. Pat. Nos. 3,169,121; 3,207,814; 4,194,038; 4,156,069; 4,430,484, 4,465,820, and 4,981,898, the disclosure regarding copolyestercarbonates from each of the U.S. patents is incorporated by reference herein.

Copolyestercarbonates useful in this invention can be available commercially and/or can be prepared by known methods in the art. For example, they can be typically obtained by the reaction of at least one dihydroxyaromatic compound with a mixture of phosgene and at least one dicarboxylic acid chloride, especially isophthaloyl chloride, terephthaloyl chloride, or both.

In addition, the polyester compositions and the polymer blend compositions useful in the food storage container(s) of this invention may also contain from 0.01 to 25% by weight of the overall composition common additives such as colorants, dyes, mold release agents, flame retardants, plasticizers, nucleating agents, stabilizers, including but not limited to, UV stabilizers, thermal stabilizers and/or reaction products thereof, fillers, and impact modifiers. For example, UV additives can be incorporated into the food storage container(s) through addition to the bulk, through application of a hard coat, or through the coextrusion of a cap layer. Examples of typical commercially available impact modifiers well known in the art and useful in this invention include, but are not limited to, ethylene/propylene terpolymers; functionalized polyolefins, such as those containing methyl acrylate and/or glycidyl methacrylate; styrene-based block copolymeric impact modifiers, and various acrylic core/shell type impact modifiers. Residues of such additives are also contemplated as part of the polyester composition.

The polyesters of the invention can comprise at least one chain extender. Suitable chain extenders include, but are not limited to, multifunctional (including, but not limited to, bifunctional) isocyanates, multifunctional epoxides, including for example, epoxylated novolacs, and phenoxy resins. In certain embodiments, chain extenders may be added at the end of the polymerization process or after the polymerization process. If added after the polymerization process, chain extenders can be incorporated by compounding or by addition during conversion processes such as injection molding or extrusion. The amount of chain extender used can vary depending on the specific monomer composition used and the physical properties desired but is generally about 0.1 percent by weight to about 10 percent by weight, preferably about 0.1 to about 5 percent by weight, based on the total weigh of the polyester.

Thermal stabilizers are compounds that stabilize polyesters during polyester manufacture and/or post polymerization, including, but not limited to, phosphorous compounds, including, but not limited to, phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphonous acid, and various esters and salts thereof. The esters can be alkyl, branched alkyl, substituted alkyl, difunctional alkyl, alkyl ethers, aryl, and substituted aryl. In one embodiment, the number of ester groups present in the particular phosphorous compound can vary from zero up to the maximum allowable based on the number of hydroxyl groups present on the thermal stabilizer used. The term “thermal stabilizer” is intended to include the reaction product(s) thereof. The term “reaction product” as used in connection with the thermal stabilizers of the invention refers to any product of a polycondensation or esterification reaction between the thermal stabilizer and any of the monomers used in making the polyester as well as the product of a polycondensation or esterification reaction between the catalyst and any other type of additive. These can be present in the polyester compositions useful in the invention.

Reinforcing materials may be useful in the compositions of this invention. The reinforcing materials may include, but are not limited to, carbon filaments, silicates, mica, clay, talc, titanium dioxide, Wollastonite, glass flakes, glass beads and fibers, and polymeric fibers and combinations thereof. In one embodiment, the reinforcing materials are glass, such as, fibrous glass filaments, mixtures of glass and talc, glass and mica, and glass and polymeric fibers.

The invention further relates to food storage container(s) described herein. These food storage container(s) include, but are not limited to, injection molded food storage container(s), injection blow molded food storage container(s), injection stretch blow molded food storage container(s), extrusion blow molded food storage container(s), extrusion stretch blow molded food storage container(s) and compression molded food storage container(s). Methods of making food storage container(s) include, but are not limited to, injection molding, extrusion blow molding, extrusion stretch blow molding, injection blow molding, and injection stretch blow molding.

For the purposes of this disclosure, the term “wt” means “weight”.

The following examples further illustrate how the food storage container(s) of the invention can be made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope thereof. Unless indicated otherwise, parts are parts by weight, temperature is in degrees C. or is at room temperature, and pressure is at or near atmospheric.

EXAMPLES Measurement Methods

The inherent viscosity of the polyesters was determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.

Unless stated otherwise, the glass transition temperature (T_(g)) was determined using a TA DSC 2920 instrument from Thermal Analyst Instruments at a scan rate of 20° C./min according to ASTM D3418.

The glycol content and the cis/trans ratio of the compositions were determined by proton nuclear magnetic resonance (NMR) spectroscopy. All NMR spectra were recorded on a JEOL Eclipse Plus 600 MHz nuclear magnetic resonance spectrometer using either chloroform-trifluoroacetic acid (70-30 volume/volume) for polymers or, for oligomeric samples, 60/40 (wt/wt) phenol/tetrachloroethane with deuterated chloroform added for lock. Peak assignments for 2,2,4,4-tetramethyl-1,3-cyclobutanediol resonances were made by comparison to model mono- and dibenzoate esters of 2,2,4,4-tetramethyl-1,3-cyclobutanediol. These model compounds closely approximate the resonance positions found in the polymers and oligomers.

The crystallization half-time, t½, was determined by measuring the light transmission of a sample via a laser and photo detector as a function of time on a temperature controlled hot stage. This measurement was done by exposing the polymers to a temperature, T_(max), and then cooling it to the desired temperature. The sample was then held at the desired temperature by a hot stage while transmission measurements were made as a function of time. Initially, the sample was visually clear with high light transmission and became opaque as the sample crystallized. The crystallization half-time was recorded as the time at which the light transmission was halfway between the initial transmission and the final transmission. T_(max) is defined as the temperature required to melt the crystalline domains of the sample (if crystalline domains are present). The T_(max) reported in the examples below represents the temperature at which each sample was heated to condition the sample prior to crystallization half time measurement. The T_(max) temperature is dependant on composition and is typically different for each polyester. For example, PCT may need to be heated to some temperature greater than 290° C. to melt the crystalline domains.

Density was determined using a gradient density column at 23° C.

The melt viscosity reported herein was measured by using a Rheometrics Dynamic Analyzer (RDA II). The melt viscosity was measured as a function of shear rate, at frequencies ranging from 1 to 400 rad/sec, at the temperatures reported. The zero shear melt viscosity (η_(o)) is the melt viscosity at zero shear rate estimated by extrapolating the data by known models in the art. This step is automatically performed by the Rheometrics Dynamic Analyzer (RDA II) software.

The polymers were dried at a temperature ranging from 80 to 100° C. in a vacuum oven for 24 hours and injection molded on a Boy 22S molding machine to give ⅛×½×5-inch and ¼×½×5-inch flexure bars. These bars were cut to a length of 2.5 inch and notched down the ½ inch width with a 10-mil notch in accordance with ASTM D256. The average Izod impact strength at 23° C. was determined from measurements on 5 specimens.

In addition, 5 specimens were tested at various temperatures using 5° C. increments in order to determine the brittle-to-ductile transition temperature. The brittle-to-ductile transition temperature is defined as the temperature at which 50% of the specimens fail in a brittle manner as denoted by ASTM D256.

Color values reported herein were determined using a Hunter Lab Ultrascan Spectra Colorimeter manufactured by Hunter Associates Lab Inc., Reston, Va. The color determinations were averages of values measured on either pellets of the polyesters or plaques or other items injection molded or extruded from them. They were determined by the L*a*b* color system of the CIE (International Commission on Illumination) (translated), wherein L* represents the lightness coordinate, a* represents the red/green coordinate, and b* represents the yellow/blue coordinate.

In addition, 10-mil films were compression molded using a Carver press at 240° C.

Unless otherwise specified, the cis/trans ratio of the 1,4 cyclohexanedimethanol used in the following examples was approximately 30/70, and could range from 35/65 to 25/75. Unless otherwise specified, the cis/trans ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol used in the following examples was approximately 50/50.

The following abbreviations apply throughout the working examples and figures:

TPA Terephthalic acid DMT Dimethyl terephthalate TMCD 2,2,4,4-tetramethyl-1,3-cyclobutanediol CHDM 1,4-cyclohexanedimethanol IV Inherent viscosity η_(o) Zero shear melt viscosity T_(g) Glass transition temperature T_(bd) Brittle-to-ductile transition temperature T_(max) Conditioning temperature for crystallization half time measurements

Example 1

This example illustrates that 2,2,4,4-tetramethyl-1,3-cyclobutanediol is more effective at reducing the crystallization rate of PCT than ethylene glycol or isophthalic acid. In addition, this example illustrates the benefits of 2,2,4,4-tetramethyl-1,3-cyclobutanediol on the glass transition temperature and density.

A variety of copolyesters were prepared as described below. These copolyesters were all made with 200 ppm dibutyl tin oxide as the catalyst in order to minimize the effect of catalyst type and concentration on nucleation during crystallization studies. The cis/trans ratio of the 1,4-cyclohexanedimethanol was 31/69 while the cis/trans ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol is reported in Table 1.

For purposes of this example, the samples had sufficiently similar inherent viscosities thereby effectively eliminating this as a variable in the crystallization rate measurements.

Crystallization half-time measurements from the melt were made at temperatures from 140 to 200° C. at 10° C. increments and are reported in Table 1. The fastest crystallization half-time for each sample was taken as the minimum value of crystallization half-time as a function of temperature, typically occurring around 170 to 180° C. The fastest crystallization half-times for the samples are plotted in FIG. 1 as a function of mole % comonomer modification to PCT.

The data shows that 2,2,4,4-tetramethyl-1,3-cyclobutanediol is more effective than ethylene glycol and isophthalic acid at decreasing the crystallization rate (i.e., increasing the crystallization half-time). In addition, 2,2,4,4-tetramethyl-1,3-cyclobutanediol increases T_(g) and lowers density.

TABLE 1 Crystallization Half-times (min) at at at at at at at Comonomer IV Density T_(g) T_(max) 140° C. 150° C. 160° C. 170° C. 180° C. 190° C. 200° C. Example (mol %)¹ (dl/g) (g/ml) (° C.) (° C.) (min) (min) (min) (min) (min) (min) (min) 1A 20.2% A² 0.630 1.198 87.5 290 2.7 2.1 1.3 1.2 0.9 1.1 1.5 1B 19.8% B 0.713 1.219 87.7 290 2.3 2.5 1.7 1.4 1.3 1.4 1.7 1C 20.0% C 0.731 1.188 100.5 290 >180 >60 35.0 23.3 21.7 23.3 25.2 1D 40.2% A² 0.674 1.198 81.2 260 18.7 20.0 21.3 25.0 34.0 59.9 96.1 1E 34.5% B 0.644 1.234 82.1 260 8.5 8.2 7.3 7.3 8.3 10.0 11.4 1F 40.1% C 0.653 1.172 122.0 260 >10 days >5 days >5 days 19204 >5 days >5 days >5 days 1G 14.3% D 0.646³ 1.188 103.0 290 55.0 28.8 11.6 6.8 4.8 5.0 5.5 1H 15.0% E 0.728⁴ 1.189 99.0 290 25.4 17.1 8.1 5.9 4.3 2.7 5.1 ¹The balance of the diol component of the polyesters in Table 1 is 1,4-cyclohexanedimethanol; and the balance of the dicarboxylic acid component of the polyesters in Table 1 is dimethyl terephthalate; if the dicarboxylic acid is not described, it is 100 mole % dimethyl terephthalate. ²100 mole % 1,4-cyclohexanedimethanol. ³A film was pressed from the ground polyester of Example 1G at 240° C. The resulting film had an inherent viscosity value of 0.575 dL/g. ⁴A film was pressed from the ground polyester of Example 1H at 240° C. The resulting film had an inherent viscosity value of 0.0.652 dL/g. where: A is Isophthalic Acid B is Ethylene Glycol C is 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (approx. 50/50 cis/trans) D is 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (98/2 cis/trans) E is 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (5/95 cis/trans)

As shown in Table 1 and FIG. 1, 2,2,4,4-tetramethyl-1,3-cyclobutanediol is more effective than other comonomers, such ethylene glycol and isophthalic acid, at increasing the crystallization half-time, i.e., the time required for a polymer to reach half of its maximum crystallinity. By decreasing the crystallization rate of PCT (increasing the crystallization half-time), amorphous articles based on 2,2,4,4-tetramethyl-1,3-cyclobutanediol-modified PCT as described herein may be fabricated by methods known in the art. As shown in Table 1, these materials can exhibit higher glass transition temperatures and lower densities than other modified PCT copolyesters.

Preparation of the polyesters shown on Table 1 is described below.

Example 1A

This example illustrates the preparation of a copolyester with a target composition of 80 mol % dimethyl terephthalate residues, 20 mol % dimethyl isophthalate residues, and 100 mol % 1,4-cyclohexanedimethanol residues (28/72 cis/trans).

A mixture of 56.63 g of dimethyl terephthalate, 55.2 g of 1,4-cyclohexanedimethanol, 14.16 g of dimethyl isophthalate, and 0.0419 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 210° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 210° C. for 5 minutes and then the temperature was gradually increased to 290° C. over 30 minutes. The reaction mixture was held at 290° C. for 60 minutes and then vacuum was gradually applied over the next 5 minutes until the pressure inside the flask reached 100 mm of Hg. The pressure inside the flask was further reduced to 0.3 mm of Hg over the next 5 minutes. A pressure of 0.3 mm of Hg was maintained for a total time of 90 minutes to remove excess unreacted diols. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 87.5° C. and an inherent viscosity of 0.63 dl/g. NMR analysis showed that the polymer was composed of 100 mol % 1,4-cyclohexanedimethanol residues and 20.2 mol % dimethyl isophthalate residues.

Example 1B

This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 20 mol % ethylene glycol residues, and 80 mol % 1,4-cyclohexanedimethanol residues (32/68 cis/trans).

A mixture of 77.68 g of dimethyl terephthalate, 50.77 g of 1,4-cyclohexanedimethanol, 27.81 g of ethylene glycol, and 0.0433 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 200° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 200° C. for 60 minutes and then the temperature was gradually increased to 210° C. over 5 minutes. The reaction mixture was held at 210° C. for 120 minutes and then heated up to 280° C. in 30 minutes. Once at 280° C., vacuum was gradually applied over the next 5 minutes until the pressure inside the flask reached 100 mm of Hg. The pressure inside the flask was further reduced to 0.3 mm of Hg over the next 10 minutes. A pressure of 0.3 mm of Hg was maintained for a total time of 90 minutes to remove excess unreacted diols. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 87.7° C. and an inherent viscosity of 0.71 dl/g. NMR analysis showed that the polymer was composed of 19.8 mol % ethylene glycol residues.

Example 1C

This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 20 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, and 80 mol % 1,4-cyclohexanedimethanol residues (31/69 cis/trans).

A mixture of 77.68 g of dimethyl terephthalate, 48.46 g of 1,4-cyclohexanedimethanol, 17.86 g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 0.046 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. This polyester was prepared in a manner similar to that described in Example 1A. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 100.5° C. and an inherent viscosity of 0.73 dl/g. NMR analysis showed that the polymer was composed of 80.5 mol % 1,4-cyclohexanedimethanol residues and 19.5 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Example 1D

This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 40 mol % dimethyl isophthalate residues, and 100 mol % 1,4-cyclohexanedimethanol residues (28/72 cis/trans).

A mixture of 42.83 g of dimethyl terephthalate, 55.26 g of 1,4-cyclohexanedimethanol, 28.45 g of dimethyl isophthalate, and 0.0419 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 210° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 210° C. for 5 minutes and then the temperature was gradually increased to 290° C. over 30 minutes. The reaction mixture was held at 290° C. for 60 minutes and then vacuum was gradually applied over the next 5 minutes until the pressure inside the flask reached 100 mm of Hg. The pressure inside the flask was further reduced to 0.3 mm of Hg over the next 5 minutes. A pressure of 0.3 mm of Hg was maintained for a total time of 90 minutes to remove excess unreacted diols. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 81.2° C. and an inherent viscosity of 0.67 dL/g. NMR analysis showed that the polymer was composed of 100 mol % 1,4-cyclohexanedimethanol residues and 40.2 mol % dimethyl isophthalate residues.

Example 1E

This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 40 mol % ethylene glycol residues, and 60 mol % 1,4-cyclohexanedimethanol residues (31/69 cis/trans).

A mixture of 81.3 g of dimethyl terephthalate, 42.85 g of 1,4-cyclohexanedimethanol, 34.44 g of ethylene glycol, and 0.0419 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 200° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 200° C. for 60 minutes and then the temperature was gradually increased to 210° C. over 5 minutes. The reaction mixture was held at 210° C. for 120 minutes and then heated up to 280° C. in 30 minutes. Once at 280° C., vacuum was gradually applied over the next 5 minutes until the pressure inside the flask reached 100 mm of Hg. The pressure inside the flask was further reduced to 0.3 mm of Hg over the next 10 minutes. A pressure of 0.3 mm of Hg was maintained for a total time of 90 minutes to remove excess unreacted diols. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 82.1° C. and an inherent viscosity of 0.64 dl/g. NMR analysis showed that the polymer was composed of 34.5 mol % ethylene glycol residues.

Example 1F

This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 40 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, and 60 mol % 1,4-cyclohexanedimethanol residues (31/69 cis/trans).

A mixture of 77.4 g of dimethyl terephthalate, 36.9 g of 1,4-cyclohexanedimethanol, 32.5 g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 0.046 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 210° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 210° C. for 3 minutes and then the temperature was gradually increased to 260° C. over 30 minutes. The reaction mixture was held at 260° C. for 120 minutes and then heated up to 290° C. in 30 minutes. Once at 290° C., vacuum was gradually applied over the next 5 minutes until the pressure inside the flask reached 100 mm of Hg. The pressure inside the flask was further reduced to 0.3 mm of Hg over the next 5 minutes. A pressure of 0.3 mm of Hg was maintained for a total time of 90 minutes to remove excess unreacted diols. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 122° C. and an inherent viscosity of 0.65 dl/g. NMR analysis showed that the polymer was composed of 59.9 mol % 1,4-cyclohexanedimethanol residues and 40.1 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Example 1G

This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 20 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues (98/2 cis/trans), and 80 mol % 1,4-cyclohexanedimethanol residues (31/69 cis/trans).

A mixture of 77.68 g of dimethyl terephthalate, 48.46 g of 1,4-cyclohexanedimethanol, 20.77 g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 0.046 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 210° C. The stirring speed was set to 200 RPM throughout the experiment. The contents of the flask were heated at 210° C. for 3 minutes and then the temperature was gradually increased to 260° C. over 30 minutes. The reaction mixture was held at 260° C. for 120 minutes and then heated up to 290° C. in 30 minutes. Once at 290° C., vacuum was gradually applied over the next 5 minutes until the pressure inside the flask reached 100 mm of Hg and the stirring speed was also reduced to 100 RPM. The pressure inside the flask was further reduced to 0.3 mm of Hg over the next 5 minutes and the stirring speed was reduced to 50 RPM. A pressure of 0.3 mm of Hg was maintained for a total time of 60 minutes to remove excess unreacted diols. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 103° C. and an inherent viscosity of 0.65 dl/g. NMR analysis showed that the polymer was composed of 85.7 mol % 1,4-cyclohexanedimethanol residues and 14.3 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Example 1H

This example illustrates the preparation of a copolyester with a target composition of 100 mol % dimethyl terephthalate residues, 20 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues (5/95 cis/trans), and 80 mol % 1,4-cyclohexanedimethanol residues (31/69 cis/trans).

A mixture of 77.68 g of dimethyl terephthalate, 48.46 g of 1,4-cyclohexanedimethanol, 20.77 g of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 0.046 g of dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 210° C. The stirring speed was set to 200 RPM at the beginning of the experiment. The contents of the flask were heated at 210° C. for 3 minutes and then the temperature was gradually increased to 260° C. over 30 minutes. The reaction mixture was held at 260° C. for 120 minutes and then heated up to 290° C. in 30 minutes. Once at 290° C., vacuum was gradually applied over the next 5 minutes with a set point of 100 mm of Hg and the stirring speed was also reduced to 100 RPM. The pressure inside the flask was further reduced to a set point of 0.3 mm of Hg over the next 5 minutes and the stirring speed was reduced to 50 RPM. This pressure was maintained for a total time of 60 minutes to remove excess unreacted diols. It was noted that the vacuum system failed to reach the set point mentioned above, but produced enough vacuum to produce a high melt viscosity, visually clear and colorless polymer with a glass transition temperature of 99° C. and an inherent viscosity of 0.73 dl/g. NMR analysis showed that the polymer was composed of 85 mol % 1,4-cyclohexanedimethanol residues and 15 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Example 2

This example illustrates that 2,2,4,4-tetramethyl-1,3-cyclobutanediol improves the toughness of PCT-based copolyesters (polyesters containing terephthalic acid and 1,4-cyclohexanedimethanol).

Copolyesters based on 2,2,4,4-tetramethyl-1,3-cyclobutanediol were prepared as described below. The cis/trans ratio of the 1,4-cyclohexanedimethanol was approximately 31/69 for all samples. Copolyesters based on ethylene glycol and 1,4-cyclohexanedimethanol were commercial polyesters. The copolyester of Example 2A (Eastar PCTG 5445) was obtained from Eastman Chemical Co. The copolyester of Example 2B was obtained from Eastman Chemical Co. under the trade name Spectar. Example 2C and Example 2D were prepared on a pilot plant scale (each a 15-lb batch) following an adaptation of the procedure described in Example 1A and having the inherent viscosities and glass transition temperatures described in Table 2 below. Example 2C was prepared with a target tin amount of 300 ppm (Dibutyltin Oxide). The final product contained 295 ppm tin. The color values for the polyester of Example 2C were L*=77.11; a*=−1.50; and b*=5.79. Example 2D was prepared with a target tin amount of 300 ppm (Dibutyltin Oxide). The final product contained 307 ppm tin. The color values for the polyester of Example 2D were L*=66.72; a*=−1.22; and b*=16.28.

Materials were injection molded into bars and subsequently notched for Izod testing. The notched Izod impact strengths were obtained as a function of temperature and are also reported in Table 2.

For a given sample, the Izod impact strength undergoes a major transition in a short temperature span. For instance, the Izod impact strength of a copolyester based on 38 mol % ethylene glycol undergoes this transition between 15 and 20° C. This transition temperature is associated with a change in failure mode; brittle/low energy failures at lower temperatures and ductile/high energy failures at higher temperatures. The transition temperature is denoted as the brittle-to-ductile transition temperature, T_(bd), and is a measure of toughness. T_(bd) is reported in Table 2 and plotted against mol % comonomer in FIG. 2.

The data shows that adding 2,2,4,4-tetramethyl-1,3-cyclobutanediol to PCT lowers T_(bd) and improves the toughness, as compared to ethylene glycol, which increases T_(bd) of PCT.

TABLE 2 Notched Izod Impact Energy (ft-lb/in) Comonomer IV T_(g) T_(bd) at at at at at at at at at at at Example (mol %)¹ (dl/g) (° C.) (° C.) −20° C. −15° C. −10° C. −5° C. 0° C. 5° C. 10° C. 15° C. 20° C. 25° C. 30° C. 2A 38.0% B 0.68 86 18 NA NA NA 1.5 NA NA 1.5 1.5 32 32 NA 2B 69.0% B 0.69 82 26 NA NA NA NA NA NA 2.1 NA 2.4 13.7 28.7 2C 22.0% C 0.66 106 −5 1.5 NA 12 23   23 NA 23   NA NA NA NA 2D 42.8% C 0.60 133 −12 2.5 2.5 11 NA 14 NA NA NA NA NA NA ¹The balance of the glycol component of the polyesters in the Table is 1,4-cyclohexanedimethanol. All polymers were prepared from 100 mole % dimethyl terephthalate. NA = Not available. where: B is Ethylene glycol C is 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (50/50 cis/trans)

Example 3

This example illustrates that 2,2,4,4-tetramethyl-1,3-cyclobutanediol can improve the toughness of PCT-based copolyesters (polyesters containing terephthalic acid and 1,4-cyclohexanedimethanol).

A copolyester based on dimethyl terephthalate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol was prepared as described below, having the composition and properties shown on Table 3. The balance up to 100 mol % of the diol component of the polyesters in Table 3 was 1,4-cyclohexanedimethanol (31/69 cis/trans).

The polyester was injection molded into both 3.2 mm and 6.4 mm thick bars and subsequently notched for Izod impact testing. The notched Izod impact strengths were obtained at 23° C. and are reported in Table 3. Density, Tg, and crystallization halftime were measured on the molded bars. Melt viscosity was measured on pellets at 290° C.

TABLE 3 Compilation of various properties for certain polyesters useful in the invention Notched Notched Izod of Izod of 3.2 mm 6.4 mm Melt thick thick Crystallization Viscosity Pellet Molded bars at bars at Specific Halftime from at 1 rad/sec TMCD % cis IV Bar IV 23° C. 23° C. Gravity Tg melt at 170° C. at 290° C. Example mole % TMCD (dl/g) (dl/g) (J/m) (J/m) (g/mL) (° C.) (min) (Poise) A 21 NA 0.715 0.692 932 482 1.179 110 56 6162 NA = Not available.

Example 3A

21.24 lb (49.71 gram-mol) dimethyl terephthalate, 12.61 lb (39.77 gram-mol) 1,4-cyclohexanedimethanol, and 6.30 lb (19.88 gram-mol) 2,2,4,4-tetramethyl-1,3-cyclobutanediol were reacted together in the presence of 200 ppm of the catalyst butyltin tris(2-ethylhexanoate). The reaction was carried out under a nitrogen gas purge in an 18-gallon stainless steel pressure vessel fitted with a condensing column, a vacuum system, and a HELICONE-type agitator. With the agitator running at 25 RPM, the reaction mixture temperature was increased to 250° C. and the pressure was increased to 20 psig. The reaction mixture was held for 2 hours at 250° C. and 20 psig pressure. The pressure was then decreased to 0 psig at a rate of 3 psig/minute. The temperature of the reaction mixture was then increased to 270° C. and the pressure was decreased to 90 mm of Hg. After a 1 hour hold time at 270° C. and 90 mm of Hg, the agitator speed was decreased to 15 RPM, the reaction mixture temperature was increased to 290° C., and the pressure was decreased to <1 mm of Hg. The reaction mixture was held at 290° C. and at a pressure of <1 mm of Hg for 60 minutes. The pressure of the pressure vessel was then increased to 1 atmosphere using nitrogen gas. The molten polymer was then extruded from the pressure vessel. The cooled, extruded polymer was ground to pass a 6-mm screen. The polymer had an inherent viscosity of 0.715 dL/g and a Tg of 110° C. X-ray analysis showed that the polyester had 223 ppm tin. NMR analysis showed that the polymer was composed of 78.6 mol % 1,4-cyclohexane-dimethanol residues and 21.4 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues. The polymer had color values of: L*=76.45, a*=−1.65, and b*=6.47.

Example 4

This example illustrates that 2,2,4,4-tetramethyl-1,3-cyclobutanediol can improve the toughness of PCT-based copolyesters (polyesters containing terephthalic acid and 1,4-cyclohexanedimethanol). Polyesters prepared in this example fall comprise more than 25 to less than 40 mol % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Copolyesters based on dimethyl terephthalate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol (31/69 cis/trans) were prepared as described below, having the composition and properties shown on Table 4. The balance up to 100 mol % of the diol component of the polyesters in Table 4 was 1,4-cyclohexanedimethanol (31/69 cis/trans).

Materials were injection molded into both 3.2 mm and 6.4 mm thick bars and subsequently notched for Izod impact testing. The notched Izod impact strengths were obtained at 23° C. and are reported in Table 4. Density, Tg, and crystallization halftime were measured on the molded bars. Melt viscosity was measured on pellets at 290° C.

TABLE 4 Compilation of various properties for certain polyesters useful in the invention Notched Notched Izod of Izod of 3.2 mm 6.4 mm Melt thick thick Crystallization Viscosity Pellet Molded bars at bars at Specific Halftime from at 1 rad/sec TMCD % cis IV Bar IV 23° C. 23° C. Gravity Tg melt at 170° C. at 290° C. Example mole % TMCD (dl/g) (dl/g) (J/m) (J/m) (g/mL) (° C.) (min) (Poise) A 27 47.8 0.714 0.678 877 878 1.178 113 280 8312 B 31 NA 0.667 0.641 807 789 1.174 116 600 6592 NA = Not available.

Example 4A

21.24 lb (49.71 gram-mol) dimethyl terephthalate, 11.82 lb (37.28 gram-mol) 1,4-cyclohexanedimethanol, and 6.90 lb (21.77 gram-mol) 2,2,4,4-tetramethyl-1,3-cyclobutanediol were reacted together in the presence of 200 ppm of the catalyst butyltin tris(2-ethylhexanoate). The reaction was carried out under a nitrogen gas purge in an 18-gallon stainless steel pressure vessel fitted with a condensing column, a vacuum system, and a HELICONE-type agitator. With the agitator running at 25 RPM, the reaction mixture temperature was increased to 250° C. and the pressure was increased to 20 psig. The reaction mixture was held for 2 hours at 250° C. and 20 psig pressure. The pressure was then decreased to 0 psig at a rate of 3 psig/minute. The temperature of the reaction mixture was then increased to 270° C. and the pressure was decreased to 90 mm of Hg. After a 1 hour hold time at 270° C. and 90 mm of Hg, the agitator speed was decreased to 15 RPM, the reaction mixture temperature was increased to 290° C., and the pressure was decreased to <1 mm of Hg. The reaction mixture was held at 290° C. and at a pressure of <1 mm of Hg until the power draw to the agitator no longer increased (50 minutes). The pressure of the pressure vessel was then increased to 1 atmosphere using nitrogen gas. The molten polymer was then extruded from the pressure vessel. The cooled, extruded polymer was ground to pass a 6-mm screen. The polymer had an inherent viscosity of 0.714 dL/g and a Tg of 113° C. NMR analysis showed that the polymer was composed of 73.3 mol % 1,4-cyclohexane-dimethanol residues and 26.7 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Example 4B

The polyester of Example 4B was prepared following a procedure similar to the one described for Example 4A. The composition and properties of this polyester are shown in Table 4.

Example 5

This example illustrates that 2,2,4,4-tetramethyl-1,3-cyclobutanediol can improve the toughness of PCT-based copolyesters (polyesters containing terephthalic acid and 1,4-cyclohexanedimethanol). Polyesters prepared in this example comprise 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues in an amount of 40 mol % or greater.

Copolyesters based on dimethyl terephthalate, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 1,4-cyclohexanedimethanol were prepared as described below, having the composition and properties shown on Table 5. The balance up to 100 mol % of the diol component of the polyesters in Table 5 was 1,4-cyclohexanedimethanol (31/69 cis/trans).

Materials were injection molded into both 3.2 mm and 6.4 mm thick bars and subsequently notched for Izod impact testing. The notched Izod impact strengths were obtained at 23° C. and are reported in Table 5. Density, Tg, and crystallization halftime were measured on the molded bars. Melt viscosity was measured on pellets at 290° C.

TABLE 5 Compilation of various properties for certain polyesters useful in the invention Notched Notched Izod of Izod of 3.2 mm 6.4 mm Melt thick thick Crystallization Viscosity Pellet Molded bars at bars at Specific Halftime from at 1 rad/sec TMCD % cis IV Bar IV 23° C. 23° C. Gravity Tg melt at 170° C. at 290° C. Example mole % TMCD (dl/g) (dl/g) (J/m) (J/m) (g/mL) (° C.) (min) (Poise) A 44 46.2 0.657 0.626 727 734 1.172 119 NA 9751 B 45 NA 0.626 0.580 748 237 1.167 123 NA 8051 C 45 NA 0.582 0.550 671 262 1.167 125 19782 5835 D 45 NA 0.541 0.493 424 175 1.167 123 NA 3275 E 59 46.6 0.604 0.576 456 311 1.156 139 NA 16537 F 45 47.2 0.475 0.450 128 30 1.169 121 NA 1614 NA = Not available.

Example 5A

21.24 lb (49.71 gram-mol) dimethyl terephthalate, 8.84 lb (27.88 gram-mol) 1,4-cyclohexanedimethanol, and 10.08 lb (31.77 gram-mol) 2,2,4,4-tetramethyl-1,3-cyclobutanediol were reacted together in the presence of 200 ppm of the catalyst butyltin tris(2-ethylhexanoate). The reaction was carried out under a nitrogen gas purge in an 18-gallon stainless steel pressure vessel fitted with a condensing column, a vacuum system, and a HELICONE-type agitator. With the agitator running at 25 RPM, the reaction mixture temperature was increased to 250° C. and the pressure was increased to 20 psig. The reaction mixture was held for 2 hours at 250° C. and 20 psig pressure. The pressure was then decreased to 0 psig at a rate of 3 psig/minute. Then the agitator speed was decreased to 15 RPM, the temperature of the reaction mixture was then increased to 290° C. and the pressure was decreased to 2 mm of Hg. The reaction mixture was held at 290° C. and at a pressure of 2 mm of Hg until the power draw to the agitator no longer increased (80 minutes). The pressure of the pressure vessel was then increased to 1 atmosphere using nitrogen gas. The molten polymer was then extruded from the pressure vessel. The cooled, extruded polymer was ground to pass a 6-mm screen. The polymer had an inherent viscosity of 0.657 dL/g and a Tg of 119° C. NMR analysis showed that the polymer was composed of 56.3 mol % 1,4-cyclohexane-dimethanol residues and 43.7 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues. The polymer had color values of: L*=75.04, a*=−1.82, and b*=6.72.

Example 5B to Example 5D

The polyesters described in Example 5B to Example 5D were prepared following a procedure similar to the one described for Example 5A. The composition and properties of these polyesters are shown in Table 5.

Example 5E

21.24 lb (49.71 gram-mol) dimethyl terephthalate, 6.43 lb (20.28 gram-mol 1,4-cyclohexanedimethanol, and 12.49 lb (39.37 gram-mol) 2,2,4,4-tetramethyl-1,3-cyclobutanediol were reacted together in the presence of 200 ppm of the catalyst butyltin tris(2-ethylhexanoate). The reaction was carried out under a nitrogen gas purge in an 18-gallon stainless steel pressure vessel fitted with a condensing column, a vacuum system, and a HELICONE-type agitator. With the agitator running at 25 RPM, the reaction mixture temperature was increased to 250° C. and the pressure was increased to 20 psig. The reaction mixture was held for 2 hours at 250° C. and 20 psig pressure. The pressure was then decreased to 0 psig at a rate of 3 psig/minute. Then the agitator speed was decreased to 15 RPM, the temperature of the reaction mixture was then increased to 290° C. and the pressure was decreased to 2 mm of Hg. The reaction mixture was held at 290° C. and at a pressure of <1 mm of Hg until the power draw to the agitator no longer increased (50 minutes). The pressure of the pressure vessel was then increased to 1 atmosphere using nitrogen gas. The molten polymer was then extruded from the pressure vessel. The cooled, extruded polymer was ground to pass a 6-mm screen. The polymer had an inherent viscosity of 0.604 dL/g and a Tg of 139° C. NMR analysis showed that the polymer was composed of 40.8 mol % 1,4-cyclohexanedimethanol residues and 59.2 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues. The polymer had color values of: L*=80.48, a*=−1.30, and b*=6.82.

Example 5F

21.24 lb (49.71 gram-mol) dimethyl terephthalate, 8.84 lb (27.88 gram-mol) 1,4-cyclohexanedimethanol, and 10.08 lb (31.77 gram-mol) 2,2,4,4-tetramethyl-1,3-cyclobutanediol were reacted together in the presence of 200 ppm of the catalyst butyltin tris(2-ethylhexanoate). The reaction was carried out under a nitrogen gas purge in an 18-gallon stainless steel pressure vessel fitted with a condensing column, a vacuum system, and a HELICONE-type agitator. With the agitator running at 25 RPM, the reaction mixture temperature was increased to 250° C. and the pressure was increased to 20 psig. The reaction mixture was held for 2 hours at 250° C. and 20 psig pressure. The pressure was then decreased to 0 psig at a rate of 3 psig/minute. The temperature of the reaction mixture was then increased to 270° C. and the pressure was decreased to 90 mm of Hg. After a 1 hour hold time at 270° C. and 90 mm of Hg, the agitator speed was decreased to 15 RPM and the pressure was decreased to 4 mm of Hg. When the reaction mixture temperature was 270° C. and the pressure was 4 mm of Hg, the pressure of the pressure vessel was immediately increased to 1 atmosphere using nitrogen gas. The molten polymer was then extruded from the pressure vessel. The cooled, extruded polymer was ground to pass a 6-mm screen. The polymer had an inherent viscosity of 0.475 dL/g and a Tg of 121° C. NMR analysis showed that the polymer was composed of 55.5 mol % 1,4-cyclohexane-dimethanol residues and 44.5 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues. The polymer had color values of: L*=85.63, a*=−0.88, and b*=4.34.

Example 6 Comparative Example

This example shows data for comparative materials in Table 6. The PC was Makrolon 2608 from Bayer, with a nominal composition of 100 mole % bisphenol A residues and 100 mole % diphenyl carbonate residues. Makrolon 2608 has a nominal melt flow rate of 20 grams/10 minutes measured at 300 C using a 1.2 kg weight. The PET was Eastar 9921 from Eastman Chemical Company, with a nominal composition of 100 mole % terephthalic acid, 3.5 mole % cyclohexanedimethanol (CHDM) and 96.5 mole % ethylene glycol. The PETG was Eastar 6763 from Eastman Chemical Company, with a nominal composition of 100 mole % terephthalic acid, 31 mole % cyclohexanedimethanol (CHDM) and 69 mole % ethylene glycol. The PCTG was Eastar DN001 from Eastman Chemical Company, with a nominal composition of 100 mole % terephthalic acid, 62 mole % cyclohexanedimethanol (CHDM) and 38 mole % ethylene glycol. The PCTA was Eastar AN001 from Eastman Chemical Company, with a nominal composition of 65 mole % terephthalic acid, 35 mole % isophthalic acid and 100 mole % cyclohexanedimethanol (CHDM). The Polysulfone was Udel 1700 from Solvay, with a nominal composition of 100 mole % bisphenol A residues and 100 mole % 4,4-dichlorosulfonyl sulfone residues. Udel 1700 has a nominal melt flow rate of 6.5 grams/10 minutes measured at 343 C using a 2.16 kg weight. The SAN was Lustran 31 from Lanxess, with a nominal composition of 76 weight % styrene and 24 weight % acrylonitrile. Lustran 31 has a nominal melt flow rate of 7.5 grams/10 minutes measured at 230 C using a 3.8 kg weight. The examples of the invention show improved toughness in 6.4 mm thickness bars compared to all of the other resins.

TABLE 6 Compilation of various properties for certain commercial polymers Notched Notched Izod of Izod of 3.2 mm 6.4 mm thick thick Crystallization Pellet Molded bars at bars at Specific Halftime from Polymer IV Bar IV 23° C. 23° C. Gravity Tg melt Example name (dl/g) (dl/g) (J/m) (J/m) (g/mL) (° C.) (min) A PC 12 MFR NA 929  108  1.20 146 NA B PCTG 0.73 0.696 NB 70 1.23 87 30 at 170° C. C PCTA 0.72 0.702 98 59 1.20 87 15 at 150° C. D PETG 0.75 0.692 83 59 1.27 80 2500 at 130° C.  E PET 0.76 0.726 45 48 1.33 78 1.5 at 170° C.  F SAN 7.5 MFR NA 21 NA 1.07 ~110 NA G PSU 6.5 MFR NA 69 NA 1.24 ~190 NA NA = Not available

Example 7

This example illustrates the effect of the amount of 2,2,4,4-tetramethyl-1,3-cyclobutanediol used for the preparation of the polyesters of the invention on the glass transition temperature of the polyesters. Polyesters prepared in this example comprise from 15 to 25 mol % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Example 7A to Example 7H

These polyesters were prepared by carrying out the ester exchange and polycondensation reactions in separate stages. The ester exchange experiments were conducted in a continuous temperature rise (CTR) reactor. The CTR was a 3000 ml glass reactor equipped with a single shaft impeller blade agitator, covered with an electric heating mantle and fitted with a heated packed reflux condenser column. The reactor was charged with 777 g (4 moles) of dimethyl terephthalate, 230 g (1.6 moles) of 2,2,4,4-tetramethyl-1,3,-cyclobutanediol, 460.8 g (3.2 moles) of cyclohexane dimethanol and 1.12 g of butyltin tris-2-ethylhexanoate (such that there will be 200 ppm tin metal in the final polymer). The heating mantle was set manually to 100% output. The set points and data collection were facilitated by a Camile process control system. Once the reactants were melted, stirring was initiated and slowly increased to 250 rpm. The temperature of the reactor gradually increased with run time. The weight of methanol collected was recorded via balance. The reaction was stopped when methanol evolution stopped or at a pre-selected lower temperature of 260° C. The oligomer was discharged with a nitrogen purge and cooled to room temperature. The oligomer was frozen with liquid nitrogen and broken into pieces small enough to be weighed into a 500 ml round bottom flask.

In the polycondensation reactions, a 500 ml round bottom flask was charged with approximately 150 g of the oligomer prepared above. The flask was equipped with a stainless steel stirrer and polymer head. The glassware was set up on a half mole polymer rig and the Camile sequence was initiated. The stirrer was positioned one full turn from the flask bottom once the oligomer melted. The temperature/pressure/stir rate sequence controlled by the Camile software for each example is reported in the following tables.

Camile Sequence for Example 7A and Example 7D

Time Temp Vacuum Stir Stage (min) (° C.) (torr) (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 290 90 50 6 5 290 1 25 7 110 290 1 25

Camile Sequence for Example 7B and Example 7C

Time Temp Vacuum Stir Stage (min) (° C.) (torr) (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 290 90 50 6 5 290 2 25 7 110 290 2 25

Camile Sequence for Example 7E to Example 7H

Time Temp Vacuum Stir Stage (min) (° C.) (torr) (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 290 90 50 6 5 290 3 25 7 110 290 3 25

The resulting polymers were recovered from the flask, chopped using a hydraulic chopper, and ground to a 6 mm screen size. Samples of each ground polymer were submitted for inherent viscosity in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C., catalyst level (Sn) by x-ray fluorescence, and color (L*, a*, b*) by transmission spectroscopy. Polymer composition was obtained by ¹H NMR. Samples were submitted for thermal stability and melt viscosity testing using a Rheometrics Mechanical Spectrometer (RMS-800).

The table below shows the experimental data for the polyesters of this example. The data shows that an increase in the level of 2,2,4,4-tetramethyl-1,3-cyclobutanediol raises the glass transition temperature in an almost linear fashion, for a constant inherent viscosity. FIG. 3 also shows the dependence of Tg on composition and inherent viscosity.

TABLE 7 Glass transition temperature as a function of inherent viscosity and composition IV η_(o) at η_(o) at η_(o) at mol % % cis (dL/ T_(g) 260° C. 275° C. 290° C. Example TMCD TMCD g) (° C.) (Poise) (Poise) (Poise) A 23.4 52.4 0.73 111 NA NA NA B 23.3 52.9 0.71 111 NA NA NA C 23.3 52.4 0.74 112 NA NA NA D 23.2 52.5 0.74 112 NA NA NA E 23.1 52.5 0.71 111 NA NA NA F 22.8 52.4 0.73 112 NA NA NA G 22.7 53 0.69 112 NA NA NA H 22.7 52 0.70 111 NA NA NA NA = Not available

Example 8

This example illustrates the effect of the amount of 2,2,4,4-tetramethyl-1,3-cyclobutanediol used for the preparation of the polyesters of the invention on the glass transition temperature of the polyesters. Polyesters prepared in this example fall comprise more than 25 to less than 40 mol % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

Dimethyl terephthalate, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol were weighed into a 500-ml single neck round bottom flask. NMR analysis on the 2,2,4,4-tetramethyl-1,3-cyclobutanediol starting material showed a cis/trans ratio of 53/47. The polyesters of this example were prepared with a 1.2/1 glycol/acid ratio with the entire excess coming from the 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Enough dibutyltin oxide catalyst was added to give 300 ppm tin in the final polymer. The flask was under a 0.2 SCFC nitrogen purge with vacuum reduction capability. The flask was immersed in a Belmont metal bath at 200° C. and stirred at 200 RPM after the reactants had melted. After about 2.5 hours, the temperature was raised to 210° C. and these conditions were held for an additional 2 hours. The temperature was raised to 285° C. (in approximately 25 minutes) and the pressure was reduced to 0.3 mm of Hg over a period of 5 minutes. The stirring was reduced as the viscosity increased, with 15 RPM being the minimum stirring used. The total polymerization time was varied to attain the target inherent viscosities. After the polymerization was complete, the Belmont metal bath was lowered and the polymer was allowed to cool to below its glass transition temperature. After about 30 minutes, the flask was reimmersed in the Belmont metal bath (the temperature had been increased to 295° C. during this 30 minute wait) and the polymer mass was heated until it pulled away from the glass flask. The polymer mass was stirred at mid level in the flask until the polymer had cooled. The polymer was removed from the flask and ground to pass a 3 mm screen. Variations to this procedure were made to produce the copolyesters described below with a targeted composition of 32 mol %.

Inherent viscosities were measured as described in the “Measurement Methods” section above. The compositions of the polyesters were determined by ¹H NMR as explained before in the Measurement Methods section. The glass transition temperatures were determined by DSC, using the second heat after quench at a rate of 20° C./min.

The table below shows the experimental data for the polyesters of this example. FIG. 3 also shows the dependence of Tg on composition and inherent viscosity. The data shows that an increase in the level of 2,2,4,4-tetramethyl-1,3-cyclobutanediol raises the glass transition temperature in an almost linear fashion, for a constant inherent viscosity.

TABLE 8 Glass transition temperature as a function of inherent viscosity and composition IV η_(o) at η_(o) at η_(o) at mol % % cis (dL/ T_(g) 260° C. 275° C. 290° C. Example TMCD TMCD g) (° C.) (Poise) (Poise) (Poise) A 32.2 51.9 0.71 118 29685 16074 8522 B 31.6 51.5 0.55 112 5195 2899 2088 C 31.5 50.8 0.62 112 8192 4133 2258 D 30.7 50.7 0.54 111 4345 2434 1154 E 30.3 51.2 0.61 111 7929 4383 2261 F 30.0 51.4 0.74 117 31476 17864 8630 G 29.0 51.5 0.67 112 16322 8787 4355 NA = Not available

Example 9

This example illustrates the effect of the amount of 2,2,4,4-tetramethyl-1,3-cyclobutanediol used for the preparation of the polyesters of the invention on the glass transition temperature of the polyesters. Polyesters prepared in this example comprise 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues in an amount of 40 mol % or greater.

Examples A to AC

These polyesters were prepared by carrying out the ester exchange and polycondensation reactions in separate stages. The ester exchange experiments were conducted in a continuous temperature rise (CTR) reactor. The CTR was a 3000 ml glass reactor equipped with a single shaft impeller blade agitator, covered with an electric heating mantle and fitted with a heated packed reflux condenser column. The reactor was charged with 777 g of dimethyl terephthalate, 375 g of 2,2,4,4-tetramethyl-1,3,-cyclobutanediol, 317 g of cyclohexane dimethanol and 1.12 g of butyltin tris-2-ethylhexanoate (such that there will be 200 ppm tin metal in the final polymer). The heating mantle was set manually to 100% output. The set points and data collection were facilitated by a Camile process control system. Once the reactants were melted, stirring was initiated and slowly increased to 250 rpm. The temperature of the reactor gradually increased with run time. The weight of methanol collected was recorded via balance. The reaction was stopped when methanol evolution stopped or at a pre-selected lower temperature of 260° C. The oligomer was discharged with a nitrogen purge and cooled to room temperature. The oligomer was frozen with liquid nitrogen and broken into pieces small enough to be weighed into a 500 ml round bottom flask.

In the polycondensation reactions, a 500 ml round bottom flask was charged with 150 g of the oligomer prepared above. The flask was equipped with a stainless steel stirrer and polymer head. The glassware was set up on a half mole polymer rig and the Camile sequence was initiated. The stirrer was positioned one full turn from the flask bottom once the oligomer melted. The temperature/pressure/stir rate sequence controlled by the Camile software for these examples is reported in the following table, unless otherwise specified below.

Camile Sequence for Polycondensation Reactions Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 290 90 50 6 5 290 6 25 7 110 290 6 25

Camile Sequence for Examples A, C, R, Y, AB, AC

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 290 90 50 6 5 290 6 25 7 110 290 6 25

For Examples B, D, F, the same sequence in the preceding table was used, except the time was 80 min in Stage 7. For Examples G and J, the same sequence in the preceding table was used, except the time was 50 min in Stage 7. For Example L, the same sequence in the preceding table was used, except the time was 140 min in Stage 7.

Camile Sequence for Example E

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 300 90 50 6 5 300 7 25 7 110 300 7 25

For Example I, the same sequence in the preceding table was used, except the vacuum was 8 torr in Stages 6 and 7. For Example O, the same sequence in the preceding table was used, except the vacuum was 6 torr in Stages 6 and 7. For Example P, the same sequence in the preceding table was used, except the vacuum was 4 torr in Stages 6 and 7. For Example Q, the same sequence in the preceding table was used, except the vacuum was 5 torr in Stages 6 and 7.

Camile Sequence for Example H

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 280 90 50 6 5 280 5 25 7 110 280 5 25

For Example U and AA, the same sequence in the preceding table was used, except the vacuum was 6 torr in Stages 6 and 7. For Example V and X, the same sequence in the preceding table was used, except the vacuum was 6 torr and stir rate was 15 rpm in Stages 6 and 7. For Example Z, the same sequence in the preceding table was used, except the stir rate was 15 rpm in Stages 6 and 7.

Camile Sequence for Example K

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 300 90 50 6 5 300 6 15 7 110 300 6 15

For Example M, the same sequence in the preceding table was used, except the vacuum was 8 torr in Stages 6 and 7. For Example N, the same sequence in the preceding table was used, except the vacuum was 7 torr in Stages 6 and 7.

Camile Sequence for Examples S and T

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 5 290 6 25 5 110 290 6 25

The resulting polymers were recovered from the flask, chopped using a hydraulic chopper, and ground to a 6 mm screen size. Samples of each ground polymer were submitted for inherent viscosity in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C., catalyst level (Sn) by x-ray fluorescence, and color (L*, a*, b*) by transmission spectroscopy. Polymer composition was obtained by 1H NMR. Samples were submitted for thermal stability and melt viscosity testing using a Rheometrics Mechanical Spectrometer (RMS-800).

Examples AD to AK and AS

The polyesters of these examples were prepared as described above for Examples A to AC, except that the target tin amount in the final polymer was 150 ppm for examples AD to AK and AS. The following tables describe the temperature/pressure/stir rate sequences controlled by the Camile software for these examples.

Camile Sequence for Examples AD, AF, and AH

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 400 50 5 110 290 400 50 6 5 290 8 50 7 110 295 8 50

For Example AD, the stirrer was turned to 25 rpm with 95 min left in Stage 7.

Camile Sequence for Example AE

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 10 245 760 0 2 5 245 760 50 3 30 283 760 50 4 3 283 175 50 5 5 283 5 50 6 5 283 1.2 50 7 71 285 1.2 50

For Example AK, the same sequence in the preceding table was used, except the time was 75 min in Stage 7.

Camile Sequence for Example AG

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 10 245 760 0 2 5 245 760 50 3 30 285 760 50 4 3 285 175 50 5 5 285 5 50 6 5 285 4 50 7 220 290 4 50

Camile Sequence for Example AI

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 285 90 50 6 5 285 6 50 7 70 290 6 50

Camile Sequence for Example AJ

Vacuum Stage Time (min) Temp (° C.) (torr) Stir (rpm) 1 5 245 760 0 2 5 245 760 50 3 30 265 760 50 4 3 265 90 50 5 110 290 90 50 6 5 290 6 25 7 110 295 6 25

Examples AL to AR

Dimethyl terephthalate, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol were weighed into a 500-ml single neck round bottom flask. The polyesters of this example were prepared with a 1.2/1 glycol/acid ratio with the entire excess coming from the 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Enough dibutyltin oxide catalyst was added to give 300 ppm tin in the final polymer. The flask was under a 0.2 SCFC nitrogen purge with vacuum reduction capability. The flask was immersed in a Belmont metal bath at 200° C. and stirred at 200 RPM after the reactants had melted. After about 2.5 hours, the temperature was raised to 210° C. and these conditions were held for an additional 2 hours. The temperature was raised to 285° C. (in approximately 25 minutes) and the pressure was reduced to 0.3 mm of Hg over a period of 5 minutes. The stirring was reduced as the viscosity increased, with 15 RPM being the minimum stirring used. The total polymerization time was varied to attain the target inherent viscosities. After the polymerization was complete, the Belmont metal bath was lowered and the polymer was allowed to cool to below its glass transition temperature. After about 30 minutes, the flask was reimmersed in the Belmont metal bath (the temperature had been increased to 295° C. during this 30 minute wait) and the polymer mass was heated until it pulled away from the glass flask. The polymer mass was stirred at mid level in the flask until the polymer had cooled. The polymer was removed from the flask and ground to pass a 3 mm screen. Variations to this procedure were made to produce the copolyesters described below with a targeted composition of 45 mol %.

Inherent viscosities were measured as described in the “Measurement Methods” section above. The compositions of the polyesters were determined by ¹H NMR as explained before in the Measurement Methods section. The glass transition temperatures were determined by DSC, using the second heat after quench at a rate of 20° C./min.

The table below shows the experimental data for the polyesters of this example. The data shows that an increase in the level of 2,2,4,4-tetramethyl-1,3-cyclobutanediol raises the glass transition temperature in an almost linear fashion, for a constant inherent viscosity. FIG. 3 also shows the dependence of Tg on composition and inherent viscosity.

TABLE 9 Glass transition temperature as a function of inherent viscosity and composition IV η_(o) at η_(o) at η_(o) at mol % % cis (dL/ T_(g) 260° C. 275° C. 290° C. Example TMCD TMCD g) (° C.) (Poise) (Poise) (Poise) A 43.9 72.1 0.46 131 NA NA NA B 44.2 36.4 0.49 118 NA NA NA C 44 71.7 0.49 128 NA NA NA D 44.3 36.3 0.51 119 NA NA NA E 46.1 46.8 0.51 125 NA NA NA F 43.6 72.1 0.52 128 NA NA NA G 43.6 72.3 0.54 127 NA NA NA H 46.4 46.4 0.54 127 NA NA NA I 45.7 47.1 0.55 125 NA NA NA J 44.4 35.6 0.55 118 NA NA NA K 45.2 46.8 0.56 124 NA NA NA L 43.8 72.2 0.56 129 NA NA NA M 45.8 46.4 0.56 124 NA NA NA N 45.1 47.0 0.57 125 NA NA NA O 45.2 46.8 0.57 124 NA NA NA P 45 46.7 0.57 125 NA NA NA Q 45.1 47.1 0.58 127 NA NA NA R 44.7 35.4 0.59 123 NA NA NA S 46.1 46.4 0.60 127 NA NA NA T 45.7 46.8 0.60 129 NA NA NA U 46 46.3 0.62 128 NA NA NA V 45.9 46.3 0.62 128 NA NA NA X 45.8 46.1 0.63 128 NA NA NA Y 45.6 50.7 0.63 128 NA NA NA Z 46.2 46.8 0.65 129 NA NA NA AA 45.9 46.2 0.66 128 NA NA NA AB 45.2 46.4 0.66 128 NA NA NA AC 45.1 46.5 0.68 129 NA NA NA AD 46.3 52.4 0.52 NA NA NA NA AE 45.7 50.9 0.54 NA NA NA NA AF 46.3 52.6 0.56 NA NA NA NA AG 46 50.6 0.56 NA NA NA NA AH 46.5 51.8 0.57 NA NA NA NA AI 45.6 51.2 0.58 NA NA NA NA AJ 46 51.9 0.58 NA NA NA NA AK 45.5 51.2 0.59 NA NA NA NA AL 45.8 50.1 0.624 125 NA NA 7696 AM 45.7 49.4 0.619 128 NA NA 7209 AN 46.2 49.3 0.548 124 NA NA 2348 AP 45.9 49.5 0.72 128 76600 40260 19110 AQ 46.0 50 0.71 131 68310 32480 17817 AR 46.1 49.6 0.383 117 NA NA 387 AS 47.2 NA 0.48 NA NA NA NA NA = Not available

Example 10

This example illustrates the effect of the predominance of the type of 2,2,4,4-tetramethyl-1,3-cyclobutanediol isomer (cis or trans) on the glass transition temperature of the polyester.

Dimethyl terephthalate, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol were weighed into a 500-ml single neck round bottom flask. The polyesters of this example were prepared with a 1.2/1 glycol/acid ratio with the entire excess coming from the 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Enough dibutyltin oxide catalyst was added to give 300 ppm tin in the final polymer. The flask was under a 0.2 SCFC nitrogen purge with vacuum reduction capability. The flask was immersed in a Belmont metal bath at 200° C. and stirred at 200 RPM after the reactants had melted. After about 2.5 hours, the temperature was raised to 210° C. and these conditions were held for an additional 2 hours. The temperature was raised to 285° C. (in approximately 25 minutes) and the pressure was reduced to 0.3 mm of Hg over a period of 5 minutes. The stirring was reduced as the viscosity increased, with 15 RPM being the minimum stirring used. The total polymerization time was varied to attain the target inherent viscosities. After the polymerization was complete, the Belmont metal bath was lowered and the polymer was allowed to cool to below its glass transition temperature. After about 30 minutes, the flask was reimmersed in the Belmont metal bath (the temperature had been increased to 295° C. during this 30 minute wait) and the polymer mass was heated until it pulled away from the glass flask. The polymer mass was stirred at mid level in the flask until the polymer had cooled. The polymer was removed from the flask and ground to pass a 3 mm screen. Variations to this procedure were made to produce the copolyesters described below with a targeted composition of 45 mol %.

Inherent viscosities were measured as described in the “Measurement Methods” section above. The compositions of the polyesters were determined by ¹H NMR as explained before in the Measurement Methods section. The glass transition temperatures were determined by DSC, using the second heat after quench at a rate of 20° C./min.

The table below shows the experimental data for the polyesters of this Example. The data shows that cis 2,2,4,4-tetramethyl-1,3-cyclobutanediol is approximately twice as effective as trans 2,2,4,4-tetramethyl-1,3-cyclobutanediol at increasing the glass transition temperature for a constant inherent viscosity.

TABLE 10 Effect of 2,2,4,4-tetramethyl-1,3-cyclobutanediol cis/trans composition on T_(g) IV η_(o) at η_(o) at η_(o) at mol % (dL/ T_(g) 260° C. 275° C. 290° C. % cis Example TMCD g) (° C.) (Poise) (Poise) (Poise) TMCD A 45.8 0.71 119 N.A. N.A. N.A. 4.1 B 43.2 0.72 122 N.A. N.A. N.A. 22.0 C 46.8 0.57 119 26306 16941 6601 22.8 D 43.0 0.67 125 55060 36747 14410 23.8 E 43.8 0.72 127 101000 62750 25330 24.5 F 45.9 0.533 119 11474 6864 2806 26.4 G 45.0 0.35 107 N.A. N.A. N.A. 27.2 H 41.2 0.38 106 1214 757 N.A. 29.0 I 44.7 0.59 123 N.A. N.A. N.A. 35.4 J 44.4 0.55 118 N.A. N.A. N.A. 35.6 K 44.3 0.51 119 N.A. N.A. N.A. 36.3 L 44.0 0.49 128 N.A. N.A. N.A. 71.7 M 43.6 0.52 128 N.A. N.A. N.A. 72.1 N 43.6 0.54 127 N.A. N.A. N.A. 72.3 O 41.5 0.58 133 15419 10253 4252 88.7 P 43.8 0.57 135 16219 10226 4235 89.6 Q 41.0 0.33 120 521 351 2261 90.4 R 43.0 0.56 134 N.A. N.A. N.A. 90.6 S 43.0 0.49 132 7055 4620 2120 90.6 T 43.1 0.55 134 12970 8443 3531 91.2 U 45.9 0.52 137 N.A. N.A. N.A. 98.1 NA = not available

Example 11

This example illustrates the preparation of a copolyester containing 100 mol % dimethyl terephthalate residues, 55 mol % 1,4-cyclohexanedimethanol residues, and 45 mol % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.

A mixture of 97.10 g (0.5 mol) dimethyl terephthalate, 52.46 g (0.36 mol) 1,4-cyclohexanedimethanol, 34.07 g (0.24 mol) 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and 0.0863 g (300 ppm) dibutyl tin oxide was placed in a 500-milliliter flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a Wood's metal bath already heated to 200° C. The contents of the flask were heated at 200° C. for 1 hour and then the temperature was increased to 210° C. The reaction mixture was held at 210° C. for 2 hours and then heated up to 290° C. in 30 minutes. Once at 290° C., a vacuum of 0.01 psig was gradually applied over the next 3 to 5 minutes. Full vacuum (0.01 psig) was maintained for a total time of about 45 minutes to remove excess unreacted diols. A high melt viscosity, visually clear and colorless polymer was obtained with a glass transition temperature of 125° C. and an inherent viscosity of 0.64 dl/g.

Example 12 Comparative Example

This example illustrates that a polyester based on 100% 2,2,4,4-tetramethyl-1,3-cyclobutanediol has a slow crystallization half-time.

A polyester based solely on terephthalic acid and 2,2,4,4-tetramethyl-1,3-cyclobutanediol was prepared in a method similar to the method described in Example 1A with the properties shown on Table 11. This polyester was made with 300 ppm dibutyl tin oxide. The trans/cis ratio of the 2,2,4,4-tetramethyl-1,3-cyclobutanediol was 65/35.

Films were pressed from the ground polymer at 320° C. Crystallization half-time measurements from the melt were made at temperatures from 220 to 250° C. at 10° C. increments and are reported in Table 11. The fastest crystallization half-time for the sample was taken as the minimum value of crystallization half-time as a function of temperature. The fastest crystallization half-time of this polyester is around 1300 minutes. This value contrasts with the fact that the polyester (PCT) based solely on terephthalic acid and 1,4-cyclohexanedimethanol (no comonomer modification) has an extremely short crystallization half-time (<1 min) as shown in FIG. 1.

TABLE 11 Crystallization Half-times (min) at at at at Comonomer IV T_(g) T_(max) 220° C. 230° C. 240° C. 250° C. (mol %) (dl/g) (° C.) (° C.) (min) (min) (min) (min) 100 mol % F 0.63 170.0 330 3291 3066 1303 1888 where: F is 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (65/35 Trans/Cis)

Example 13

Sheets comprising a polyester that had been prepared with a target composition of 100 mole % terephthalic acid residues, 80 mole % 1,4-cyclohexanedimethanol residues, and 20 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues were produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 177 mil and then various sheets were sheared to size. Inherent viscosity and glass transition temperature were measured on one sheet. The sheet inherent viscosity was measured to be 0.69 dl/g. The glass transition temperature of the sheet was measured to be 106° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 2 weeks. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example G). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 106° C. can be thermoformed under the conditions shown below, as evidenced by these sheets having at least 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 86 145 501 64 N B 100 150 500 63 N C 118 156 672 85 N D 135 163 736 94 N E 143 166 760 97 N F 150 168 740 94 L G 159 172 787 100 L

Example 14

Sheets comprising a polyester that had been prepared with a target composition of 100 mole % terephthalic acid residues, 80 mole % 1,4-cyclohexanedimethanol residues, and 20 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues were produced using a 3.5 inch single screw. A sheet was extruded continuously, gauged to a thickness of 177 mil and then various sheets were sheared to size. Inherent viscosity and glass transition temperature were measured on one sheet. The sheet inherent viscosity was measured to be 0.69 dl/g. The glass transition temperature of the sheet was measured to be 106° C. Sheets were then conditioned at 100% relative humidity and 25° C. for 2 weeks. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 60/40/40% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example G). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 106° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having at least 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 141 154 394 53 N B 163 157 606 82 N C 185 160 702 95 N D 195 161 698 95 N E 215 163 699 95 L F 230 168 705 96 L G 274 174 737 100 H H 275 181 726 99 H

Example 15 Comparative Example

Sheets consisting of Kelvx 201 were produced using a 3.5 inch single screw extruder. Kelvx is a blend consisting of 69.85% PCTG (Eastar from Eastman Chemical Co. having 100 mole % terephthalic acid residues, 62 mole % 1,4-cyclohexanedimethanol residues, and 38 mole % ethylene glycol residues); 30% PC (bisphenol A polycarbonate); and 0.15% Weston 619 (stabilizer sold by Crompton Corporation). A sheet was extruded continuously, gauged to a thickness of 177 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 100° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 2 weeks. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example E). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 100° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having at least 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 90 146 582 75 N B 101 150 644 83 N C 111 154 763 98 N D 126 159 733 95 N E 126 159 775 100 N F 141 165 757 98 N G 148 168 760 98 L

Example 16 Comparative Example

Sheets consisting of Kelvx 201 were produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 177 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 100° C. Sheets were then conditioned at 100% relative humidity and 25° C. for 2 weeks. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 60/40/40% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example H). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 100° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 110 143 185 25 N B 145 149 529 70 N C 170 154 721 95 N D 175 156 725 96 N E 185 157 728 96 N F 206 160 743 98 L G 253 NR 742 98 H H 261 166 756 100 H NR = Not recorded

Example 17 Comparative Example

Sheets consisting of PCTG 25976 (100 mole % terephthalic acid residues, 62 mole % 1,4-cyclohexanedimethanol residues, and 38 mole % ethylene glycol residues) were produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 87° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.17 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example A). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 87° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 102 183 816 100 N B 92 171 811 99 N C 77 160 805 99 N D 68 149 804 99 N E 55 143 790 97 N F 57 138 697 85 N

Example 18 Comparative Example

A miscible blend consisting of 20 wt % Teijin L-1250 polycarbonate (a bisphenol-A polycarbonate), 79.85 wt % PCTG 25976, and 0.15 wt % Weston 619 was produced using a 1.25 inch single screw extruder. Sheets consisting of the blend were then produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 94° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.25 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example A). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 94° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 92 184 844 100 H B 86 171 838 99 N C 73 160 834 99 N D 58 143 787 93 N E 55 143 665 79 N

Example 19 Comparative Example

A miscible blend consisting of 30 wt % Teijin L-1250 polycarbonate, 69.85 wt % PCTG 25976, and 0.15 wt % Weston 619 was produced using a 1.25 inch single screw extruder. Sheets consisting of the blend were then produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 99° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.25 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example A). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 99° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 128 194 854 100 H B 98 182 831 97 L C 79 160 821 96 N D 71 149 819 96 N E 55 145 785 92 N F 46 143 0 0 NA G 36 132 0 0 NA NA = not applicable. A value of zero indicates that the sheet was not formed because it did not pull into the mold (likely because it was too cold).

Example 20 Comparative Example

A miscible blend consisting of 40 wt % Teijin L-1250 polycarbonate, 59.85 wt % PCTG 25976, and 0.15 wt % Weston 619 was produced using a 1.25 inch single screw extruder. Sheets consisting of the blend were then produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 105° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.265 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Examples 8A to 8E). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 105° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 111 191 828 100 H B 104 182 828 100 H C 99 179 827 100 N D 97 177 827 100 N E 78 160 826 100 N F 68 149 759 92 N G 65 143 606 73 N

Example 21 Comparative Example

A miscible blend consisting of 50 wt % Teijin L-1250 polycarbonate, 49.85 wt % PCTG 25976, and 0.15 wt % Weston 619 was produced using a 1.25 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 111° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.225 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Examples A to D). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 111° C. can be thermoformed under the conditions shown below, as evidenced by the production of sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 118 192 815 100 H B 99 182 815 100 H C 97 177 814 100 L D 87 171 813 100 N E 80 160 802 98 N F 64 154 739 91 N G 60 149 0 0 NA NA = not applicable. A value of zero indicates that the sheet was not formed because it did not pull into the mold (likely because it was too cold).

Example 22 Comparative Example

A miscible blend consisting of 60 wt % Teijin L-1250 polycarbonate, 39.85 wt % PCTG 25976, and 0.15 wt % Weston 619 was produced using a 1.25 inch single screw extruder. Sheets consisting of the blend were then produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 117° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.215 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example A). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 117° C. cannot be thermoformed under the conditions shown below, as evidenced by the inability to produce sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 114 196 813 100 H B 100 182 804 99 H C 99 177 801 98 L D 92 171 784 96 L E 82 168 727 89 L F 87 166 597 73 N

Example 23 Comparative Example

A miscible blend consisting of 65 wt % Teijin L-1250 polycarbonate, 34.85 wt % PCTG 25976, and 0.15 wt % Weston 619 was produced using a 1.25 inch single screw extruder. Sheets consisting of the blend were then produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 120° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.23 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example A). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 120° C. cannot be thermoformed under the conditions shown below, as evidenced by the inability to produce sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 120 197 825 100 H B 101 177 820 99 H C 95 174 781 95 L D 85 171 727 88 L E 83 166 558 68 L

Example 24 Comparative Example

A miscible blend consisting of 70 wt % Teijin L-1250 polycarbonate, 29.85 wt % PCTG 25976, and 0.15 wt % Weston 619 was produced using a 1.25 inch single screw extruder. Sheets consisting of the blend were then produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 123° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.205 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw, and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Examples A and B). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 123° C. cannot be thermoformed under the conditions shown below, as evidenced by the inability to produce sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 126 198 826 100 H B 111 188 822 100 H C 97 177 787 95 L D 74 166 161 19 L E 58 154 0 0 NA F 48 149 0 0 NA NA = not applicable. A value of zero indicates that the sheet was not formed because it did not pull into the mold (likely because it was too cold).

Example 25 Comparative Example

Sheets consisting of Teijin L-1250 polycarbonate were produced using a 3.5 inch single screw extruder. A sheet was extruded continuously, gauged to a thickness of 118 mil and then various sheets were sheared to size. The glass transition temperature was measured on one sheet and was 149° C. Sheets were then conditioned at 50% relative humidity and 60° C. for 4 weeks. The moisture level was measured to be 0.16 wt %. Sheets were subsequently thermoformed into a female mold having a draw ratio of 2.5:1 using a Brown thermoforming machine. The thermoforming oven heaters were set to 70/60/60% output using top heat only. Sheets were left in the oven for various amounts of time in order to determine the effect of sheet temperature on the part quality as shown in the table below. Part quality was determined by measuring the volume of the thermoformed part, calculating the draw and visually inspecting the thermoformed part. The draw was calculated as the part volume divided by the maximum part volume achieved in this set of experiments (Example A). The thermoformed part was visually inspected for any blisters and the degree of blistering rated as none (N), low (L), or high (H). The results below demonstrate that these thermoplastic sheets with a glass transition temperature of 149° C. cannot be thermoformed under the conditions shown below, as evidenced by the inability to produce sheets having greater than 95% draw and no blistering, without predrying the sheets prior to thermoforming.

Thermoforming Conditions Part Quality Sheet Part Heat Time Temperature Volume Blisters Example (s) (° C.) (mL) Draw (%) (N, L, H) A 152 216 820 100 H B 123 193 805 98 H C 113 191 179 22 H D 106 188 0 0 H E 95 182 0 0 NA F 90 171 0 0 NA NA = not applicable. A value of zero indicates that the sheet was not formed because it did not pull into the mold (likely because it was too cold).

It can be clearly seen from a comparison of the data in the above relevant working examples that the polyesters of the present invention offer a definite advantage over the commercially available polyesters with regard to glass transition temperature, density, slow crystallization rate, melt viscosity, and toughness.

The invention has been described in detail with reference to the embodiments disclosed herein, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 

1. A food storage container comprising at least one polyester composition comprising at least one polyester, which comprises: (a) a dicarboxylic acid component comprising: i) 70 to 100 mole % of terephthalic acid residues; ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having up to 20 carbon atoms; and iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues having up to 16 carbon atoms; and (b) a glycol component comprising: i) 20 to 30 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and ii) 70 to 80 mole % of 1,4-cyclohexanedimethanol residues, wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; wherein the inherent viscosity of the polyester is from 0.60 to 0.75 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; wherein the polyester has a Tg of from 100 to 130° C.; wherein said polyester composition contains no polycarbonate; wherein the melt viscosity of said polyester is less than 10,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C.; and wherein the polyester has a notched Izod impact strength of at least 7.5 ft-lb/inch at 23° C. according to ASTM D256 with a 10-mil notch in a ⅛ inch thick bar.
 2. The food storage container of claim 1, wherein the inherent viscosity of the polyester is from 0.65 to 0.75 dL/g.
 3. The food storage container of claim 1, wherein the inherent viscosity of the polyester is from 0.60 to 0.70 dL/g.
 4. The food storage container of claim 1, wherein the inherent viscosity of the polyester is from 0.60 to 0.68 dL/g.
 5. The food storage container of claim 1, wherein the inherent viscosity of the polyester is from 0.60 to 0.65 dL/g.
 6. The food storage container of claim 1, wherein the inherent viscosity of the polyester is from 0.60 to 0.72 dL/g.
 7. The food storage container of claim 1, wherein the polyester has a Tg of 110° C.
 8. The food storage container of claim 1, wherein the polyester has a Tg of 110 to 125° C.
 9. The food storage container of claim 1, wherein the polyester has a Tg of 100 to 120° C.
 10. The food storage container of claim 1, wherein the polyester has a Tg of 100 to 115° C.
 11. The food storage container of claim 6, wherein the polyester has a Tg of 100 to 125° C.
 12. The food storage container of claim 1, wherein the glycol component of the polyester comprises 20 to 25 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 75 to 80 mole % 1,4-cyclohexanedimethanol residues.
 13. The food storage container of claim 1, wherein the glycol component of the polyester comprises 25 to 30 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and 70 to 75 mole % 1,4-cyclohexanedimethanol residues.
 14. The food storage container of claim 1, wherein the dicarboxylic acid component comprises 80 to 100 mole % of terephthalic acid residues.
 15. The food storage container of claim 1, wherein the dicarboxylic acid component comprises 90 to 100 mole % of terephthalic acid residues.
 16. The food storage container of claim 1, wherein the dicarboxylic acid component comprises 95 to 100 mole % of terephthalic acid residues.
 17. The food storage container of claim 1, wherein the polyester comprises from 0.1 to 10 mole % of 1,3-propanediol residues, 1,4-butanediol residues, or a mixture thereof.
 18. The food storage container of claim 1, wherein the polyester comprises from 0.1 to 5 mole % of 1,3-propanediol residues, 1,4-butanediol residues, or a mixture thereof.
 19. The food storage, container of claim 1, wherein the polyester comprises from 0.01 to 10 mole % of ethylene glycol residues.
 20. The food storage container of claim 1, wherein the 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues are a mixture comprising greater than 50 mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and less than 50 mole % of trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.
 21. The food storage container of claim 1, wherein the 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues are a mixture comprising greater than 55 mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and less than 45 mole % of trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol residues.
 22. The food storage container of claim 1, wherein the 2,2,4,4-tetramethyl-1,3-cyclobutanediol are a mixture comprising greater than 50 mole % of cis-2,2,4,4-tetramethyl-1,3-cyclobutanediol residues and less than 50 mole % of trans-2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, and wherein the dicarboxylic acid component comprises 80 to 100 mole % of terephthalic acid residues.
 23. The food storage container of claim 1, wherein the polyester composition comprises at least one polymer chosen from poly(etherimides), polyphenylene oxides, poly(phenylene oxide)/polystyrene blends, polystyrene resins, polyphenylene sulfides, polyphenylene sulfide/sulfones, polysulfones; polysulfone ethers, poly(ether-ketones), polyamides, polystyrene, polystyrene copolymers, styrene acrylonitrile copolymers, acrylonitrile butadiene styrene copolymers, poly(methylmethacrylate), or acrylic copolymers.
 24. The food storage container of claim 1, wherein the polyester comprises residues of at least one branching agent in the amount of 0.01 to 5 mole %.
 25. The food storage container of claim 1, wherein the polyester comprises residues of at least one branching agent in the amount of 0.01 to 10 mole %.
 26. The food storage container of claim 1, wherein the melt viscosity of the polyester is less than 6,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C.
 27. The food storage container of claim 1, wherein the polyester has a crystallization half-time of greater than 100 minutes at 170° C.
 28. The food storage container of claim 1, wherein the polyester has a crystallization half-time of greater than 1,000 minutes at 170° C.
 29. The food storage container of claim 1, wherein the polyester has a crystallization half-time of greater than 10,000 minutes at 170° C.
 30. The food storage container of claim 1, wherein the polyester composition has a density of less than 1.3 g/ml at 23° C.
 31. The food storage container of claim 1, wherein the polyester composition comprises at least one thermal stabilizer or a reaction product thereof.
 32. The food storage container of claim 1, wherein the yellowness index of the polyester according to ASTM D-1925 is less than
 50. 33. The food storage container of claim 1, wherein the polyester has a notched Izod impact strength of at least 10-ft-lbs/in at 23° C. according to ASTM D256 with a 10-mil notch in a ⅛-inch thick bar.
 34. The food storage container of claim 1, wherein the polyester has a notched Izod impact strength of at least 10 ft-lbs/in at 23° C. according to ASTM D256 with a 10-mil notch in a ¼-inch thick bar.
 35. The food storage container of claim 1, wherein the polyester comprises the residue of at least one catalyst comprising a tin compound or a reaction product thereof.
 36. The food storage container of claim 1, wherein the food storage container is chosen from buffet steam pans, buffet steam trays, food pans, beverage dispensers, and food storage boxes.
 37. The food storage container of claim 1, wherein the food storage container is formed by extrusion.
 38. The food storage container of claim 1, wherein the food storage container is produced by compression molding.
 39. The food storage container of claim 1, wherein the food storage container is formed by injection molding.
 40. A food storage container comprising at least one polyester composition comprising at least one polyester, which comprises: (a) a dicarboxylic acid component comprising: i) 70 to 100 mole % of terephthalic acid residues; ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having up to 20 carbon atoms; and iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues having up to 16 carbon atoms; (b) a glycol component comprising: i) 20 to 30 mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and ii) 70 to 80 mole % of 1,4-cyclohexanedimethanol residues; and (c) residues of at least one branching agent; wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; wherein the inherent viscosity of the polyester is from 0.60 to 0.75 dL/g as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; wherein said polyester composition contains no polycarbonate; wherein the melt viscosity of said polyester is less than 10,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C.; and wherein the polyester has a notched Izod impact strength of at least 7.5 ft-lb/inch at 23° C. according to ASTM D256 with a 10-mil notch in a ⅛ inch thick bar, wherein the polyester has a Tg of from 100 to 130° C.
 41. The food storage container of claim 40, wherein the inherent viscosity of the polyester is from 0.65 to 0.75 dL/g.
 42. The food storage container of claim 40, wherein the inherent viscosity of the polyester is from 0.60 to 0.68 dL/g.
 43. The food storage container of claim 40, wherein the inherent viscosity of the polyester is from 0.60 to 0.70 dL/g.
 44. The food storage container of claim 40, wherein the inherent viscosity of the polyester is from 0.60 to 0.72 dL/g.
 45. The food storage container of claim 40, wherein the polyester has a Tg of 110° C.
 46. The food storage container of claim 40, wherein the food storage container is chosen from buffet steam pans, buffet steam trays, food pans, beverage dispensers, and food storage boxes.
 47. A food storage container comprising at least one polyester composition comprising: I. at least one polyester which comprises: (a) a dicarboxylic acid component comprising: i) 70 to 100 mole % of terephthalic acid residues; ii) 0 to 30 mole % of aromatic dicarboxylic acid residues having up to 20 carbon atoms; and iii) 0 to 10 mole % of aliphatic dicarboxylic acid residues having up to 16 carbon atoms; and (b) a glycol component comprising: i) 20 to 3040-mole % of 2,2,4,4-tetramethyl-1,3-cyclobutanediol residues; and) ii) 70 to 80 mole % of 1,4-cyclohexanedimethanol residues, wherein the total mole % of the dicarboxylic acid component is 100 mole %, the total mole % of the glycol component is 100 mole %; II. at least one thermal stabilizer or the reaction product thereof or residues thereof; wherein the inherent viscosity of the polyester is from 0.60 to 0.75 dLg as determined in 60/40 (wt/wt) phenol/tetrachloroethane at a concentration of 0.5 g/100 ml at 25° C.; wherein the melt viscosity of said polyester is less than 10,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C.; wherein the polyester has a Tg of from 100° C.; wherein said polyester composition contains no polycarbonate; and wherein the polyester has a notched Izod impact strength of at least 7.5 ft-lb/inch at 23° C. according to ASTM D256 with a 10-mil notch in a ⅛ inch thick bar.
 48. The food storage container of claim 47, wherein the inherent viscosity of the polyester is from 0.65 to 0.75 dL/g.
 49. The food storage container of claim 47, wherein the inherent viscosity of the polyester is from 0.60 to 0.68 dL/g.
 50. The food storage container of claim 47, wherein the inherent viscosity of the polyester is from 0.60 to 0.72 dL/g.
 51. The food storage container of claim 47, wherein the polyester has a Tg of 110 to 130° C.
 52. The food storage container of claim 47, wherein the food storage container is chosen from buffet steam pans, buffet steam trays, food pans, beverage dispensers, and food storage boxes.
 53. The food storage container of claim 1, wherein the wherein the melt viscosity of the polyester is less than 6,000 poise as measured at 1 radian/second (rad/sec) on a rotary melt rheometer at 290° C.
 54. The food storage container of claim 40 or 47 wherein said polyester has a melt viscosity of less than 6,000 poise as measured at 1 radian/second on a rotary melt rheometer at 290° C.
 55. The food storage container of claim 1, 40 or 47, wherein the polyester has a b* value of from −10 to less than 10 and a L* value from 50 to 90 according to the L*, a* and b* color system of the CIE (International Commission on Illumination.
 56. The food storage container of claim 40 or 47, wherein the polyester compositions comprises residues from at least one branching agent in the amount of 0.01 to 10 mole % based on the total mole percentage of the diacid residues or diol residues.
 57. The food storage container of claim 40 or 47, wherein the polyester compositions comprises residues from at least one branching agent in the amount of 0.01 to 5 mole % based on the total mole percentage of the diacid residues or diol residues.
 58. The food storage container of claim 1, 40, or 47, wherein said polyester comprises residues from at least one branching agent in an amount of 0.1 to 0.7 mole % based on the total mole percentage of the diacid residues or diol residues.
 59. The food storage container of claim 1, 40, or 47, wherein said polyester comprises residues from at least one branching agent selected from trimellitic acid, trimellitic anhydride, pyromellitic dianhydride, trimethylolpropane, glycerol, pentaerythritol, citric acid, tartaric acid, or 3-hydroxyglutaric acid.
 60. The food storage container of claim 1, 40 or 47, wherein said polyester comprises residues from trimellitic anhydride.
 61. The food storage container of claim 1, 40 or 47, wherein the polyester comprises a thermal stabilizer which is a phosphorus compound chosen from at least one of phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphonous acid, or an ester or salt thereof.
 62. The food storage container of claim 40 or 47, wherein the polyester has a notched Izod impact strength of at least 10-ft-lbs/in at 23° C. according to ASTM D256 with a 10-mil notch in a ⅛-inch thick bar.
 63. The food storage container of claim 40 or 47, wherein the polyester has a notched Izod impact strength of at least 10 ft-lbs/in at 23° C. according to ASTM D256 with a 10-mil notch in a ¼-inch thick bar. 